Gallagher was born in Ballyshannon, County Donegal; his father, Daniel, was employed by the Irish Electricity Supply Board, who were constructing a hydro-electric power plant on the Erne River above the town. The family moved, first to Derry City, where his younger brother Dónal was born in 1949, and then to Cork, where the two brothers were raised, and where Rory attended the North Monastery School. Their father had played the accordion and sang with the Tir Chonaill Ceile Band whilst in Donegal; their mother Monica was a singer and acted with the Abbey Players in Ballyshannon. The Theatre in Ballyshannon where Monica once acted is now called the Rory Gallagher Theatre.

Both sons were musically inclined and encouraged by their parents. At age nine, Gallagher received his first guitar from them. He built on his burgeoning ability on ukulele in teaching himself to play the guitar and perform at minor functions. After winning a talent contest when he was twelve, Gallagher began performing in his adolescence with both his acoustic guitar, and an electric guitar he bought with his prize money. However, it was his purchase three years later of a 1961 Fender Stratocaster for £100 that became his primary instrument and most associated with him for the span of his lifetime.

Gallagher was initially attracted to skiffle after hearing Lonnie Donegan on the radio. Donegan frequently covered blues and folk performers from the United States. He relied entirely on radio programs and television. Occasionally, the jazz programs from the BBC would play some blues numbers, and he slowly found some song books for guitar, where he found the names of the actual composers of blues pieces. While still in school, playing songs by Buddy Holly and Eddie Cochran, he discovered his greatest influence in Muddy Waters. Subsequently, Gallagher began experimenting with folk, blues, and rock music. Unable to find or afford record albums, Gallagher stayed up late to hear Radio Luxembourg and AFN where the radio brought him his only exposure to the actual songwriters and musicians whose music moved him most. Influences he discovered, and cited as he progressed, included Woody Guthrie, Big Bill Broonzy, and Lead Belly. Initially, Gallagher struck out after just an acoustic sound. Singing and later using a brace for his harmonica, Gallagher taught himself to play slide guitar. Further, throughout the next few years of his musical development, Gallagher began learning to play alto saxophone, bass, mandolin, banjo, and the coral sitar with varying degrees of proficiency. By his mid-teens, he began experimenting heavily with different blues styles.

Gallagher began playing after school with Irish showbands, while still a young teenager. In 1963, he joined one named Fontana, a sextet playing the popular hit songs of the day. The band toured Ireland and the United Kingdom, earning the money for the payments that were due on his Stratocaster guitar. Gallagher began to influence the band's repertoire, beginning its transition from mainstream pop music, skirting along some of Chuck Berry's songs and by 1965, he had successfully molded Fontana into "The Impact", with a change in their lineup into an R&B group that played gigs in Ireland and Spain until disbanding in London. Gallagher left with the bassist and drummer to perform as a trio in Hamburg, Germany. In 1966, Gallagher returned to Ireland and, experimenting with other musicians back home in Cork, decided to form his own band.

Having completed a musical apprenticeship in the showbands, and influenced by the increasing popularity of beat groups during the early 1960s, Gallagher formed "The Taste", which was later renamed simply, "Taste", a blues rock and R&B power trio, in 1966. Initially, the band was composed of Gallagher and two Cork musicians, Norman Damery and Eric Kitteringham, however, by 1968, they were replaced with two musicians from Belfast, featuring Gallagher on guitar and vocals, drummer John Wilson, and bassist Richard McCracken. Performing extensively in the United Kingdom, the group played regularly at the Marquee Club, supporting both Cream at their Royal Albert Hall farewell concert, and the blues supergroup Blind Faith on a tour of North America. Managed by Eddie Kennedy, the trio released the albums Taste and On The Boards, and two live recordings, Live Taste and Live at the Isle of Wight. The latter appeared long after the band's break-up, which occurred shortly after their appearance at the 1970 Isle of Wight Festival.

After the break-up of Taste, Gallagher toured under his own name, hiring former Deep Joy bass player Gerry McAvoy to play on Gallagher's self-titled debut album, Rory Gallagher. It was the beginning of a twenty-year musical relationship between Gallagher and McAvoy; the other band member was drummer Wilgar Campbell. The 1970s were Gallagher's most prolific period. He produced ten albums in that decade, including two live albums, Live in Europe and Irish Tour '74. November 1971 saw the release of his album, Deuce. In the same year he was voted Melody Maker's International Top Musician of the Year, ahead of Eric Clapton. However, despite a number of his albums from this period reaching the UK Albums Chart, Gallagher did not attain major star status.

Gallagher played and recorded what he said was "in me all the time, and not just something I turn on ...". Though he sold over thirty million albums worldwide, it was his marathon live performances that won him greatest acclaim. He is documented in the 1974 film Irish Tour '74, directed by Tony Palmer. During the heightened periods of political unrest in Ireland, as other artists were warned not to tour, Gallagher was resolute about touring Ireland at least once a year during his career, winning him the dedication of thousands of fans, and in the process, becoming a role model for other aspiring young Irish musicians. Gallagher himself admitted in several interviews that at first there were not any international Irish acts until Van Morrison, Gallagher, and later, Phil Lynott and Thin Lizzy grew popular during the 1970s. The line-up which included Rod de'Ath on drums and Lou Martin on keyboards, performed together between 1973 and 1978. However, he eventually dropped down to just bass, guitar and drums, and his act became a power trio. Other releases from that period include Against the Grain, Calling Card, Photo-Finish and Top Priority. Gerry McAvoy has stated that the Gallagher band performed several TV and radio shows across Europe, including Beat-Club in Bremen, Germany and the Old Grey Whistle Test. He recorded two Peel Sessions, both in February 1973 and containing the same tracks, but only the first was broadcast. Along with Little Feat and Roger McGuinn, Gallagher performed the first Rockpalast live concert at the Grugahalle, Essen, Germany in 1977.

Gallagher collaborated with Jerry Lee Lewis and Muddy Waters on their respective London Sessions in the mid-1970s. He played on Lonnie Donegan's final album. He was David Coverdale's second choice (after Jeff Beck) to replace Ritchie Blackmore in Deep Purple. Gallagher chose to perform in his own band.

In the 1980s he continued recording, producing Jinx, Defender, and Fresh Evidence. After Fresh Evidence, he embarked on a tour of the United States. In addition he played with Box of Frogs which was a band formed in 1983 by former members of The Yardbirds, who released their first album in 1984. Former Yardbirds guitarists Jeff Beck and Jimmy Page also guested on their first and second albums, respectively. Becoming obsessive over details and plagued by self-doubt, Gallagher nevertheless retained a loyal fanbase. During this period he stated "I agonize too much".

Notes from San Francisco, an album of unreleased studio tracks and a San Francisco 1979 concert was released in May 2011.

Rory Gallagher (guitar, vocals)

1970–1972: Gerry McAvoy, bass guitarist, and drummer Wilgar Campbell.

1972–1976: Gerry McAvoy (bass), keyboardist Lou Martin, and drummer Rod de'Ath.

1976–1981: Gerry McAvoy (bass), Ted McKenna (drums)

1981–1991: Gerry McAvoy (bass), Brendan O'Neil (drums) + frequent guest: Mark Feltham (harmonica)

1992–1994: David Levy (bass), Jim Levaton (keyboards), John Cooke (keyboards), Richard Newman (drums) and frequent guest Mark Feltham, on harmonica.

Gallagher was always associated with his well-worn sunburst 1961 Stratocaster (Serial Number 64351), which his brother Donal has officially retired.

It was reputedly the first in Ireland, and was ordered from Fender by Jim Connolly, a showband member performing with The Irish Showband. Connolly ordered a cherry red Stratocaster through Crowley's music shop in Cork in 1961. When Fender shipped a sunburst Stratocaster instead, it was put up on sale in 1963 as a second-hand instrument, which Gallagher bought in August 1963 for just shy of £100 at Crowley's Music Store on Cork's McCurtain Street. Note: the shop was at 10 Merchants Quay at the time of purchase.

The guitar was extensively modified by Gallagher. The tuning pegs are odd (5 Sperzel pegs and one Gotoh), and all of these have been found to be replacements. Second, it is thought that the nut has been replaced and interchanged a number of times. Third, the scratchplate was changed during Gallagher's time with Taste.

The pickups —none of which are original— were also changed. The final modification was that of the wiring: Gallagher disconnected the bottom tone pot and rewired it so he had just a master tone control along with the master volume control. He also installed a 5-way selector switch in place of the vintage 3-way one.

The most notable effect that the years of touring have had on the guitar is the almost complete removal of its original sunburst finish. Although the Strat was left abandoned in a rainy ditch for days after being stolen from the back of a tour van in Dublin, this is not believed to have caused any ill effect. All of the wear was caused by Rory's playing, not misuse. A borrowed Telecaster was also stolen at the same time but never recovered. When the Strat was recovered after two weeks, Gallagher swore he would never sell it or paint it after that.

It also had a period of time of having a replacement neck, with the original neck bowing due to the amount of moisture it absorbed during continuous touring. The neck was taken off and left to settle, and was eventually reunited with the Strat after returning to its correct shape. Other quirks include a 'hump' in the scratch plate which moves the neck pickup closer to the neck on the bass side, and a replacement of all of the pickups, though this replacement was due to damage rather than the perception of a tonal inadequacy.

One final point of interest is that one of the clay double-dot inlays at the 12th fret fell out and was replaced with a plastic one, which is why it's whiter than the other clay inlays.

On Friday the 21st and Saturday the 22nd of October 2011, Rory's brother Donal brought the guitar out of retirement in order to allow Joe Bonamassa to perform with it on his two nights at the London Hammersmith Apollo. Joe opened both night's performances with his rendition of "Cradle Rock" using Rory's Stratocaster. Photos and video of the performance can be seen on the official Rory Gallagher website.

Rory's biographer Marcus Connaughton believes the Strat was the key to Rory’s sound. Rory could talk about it all night. ‘It’s dated November 1961 – in certain people’s opinions this is when Fender hit their peak. I like the maple neck. Like on the earlier guitars, they’re probably a bit more crisp, but there’s a warmth to this, a mellowness because of the rosewood neck. This is the best, it’s my life, this is my best friend. It’s almost like knowing its weak spots are strong spots. I don’t like to get sentimental about these things, but when you spend thirty years of your life with the same instrument it’s like a walking memory bank of your life there in your arms.’

Gallagher used various makes and models of amplifiers during his career. In general, however, he preferred smaller 'combo' amplifiers to the larger, more powerful 'stacks' popular with rock and hard rock guitarists. To make up for the relative lack of power on stage, he would often link several different combo amps together.

When Gallagher was with Taste, he used a single Vox AC30 with a Dallas Rangemaster treble booster plugged into the 'normal' input. Examples of this sound can be heard on the Taste albums, as well as the album Live in Europe. Brian May, of the band Queen, has admitted in interviews that as a young man, he was inspired to use a Vox AC30 and treble booster setup after meeting Gallagher and asking him how he got his sound. The British company, Flynn Amps, now makes a Rory Gallagher Signature Hawk Treble Booster pedal based on Gallagher's original unit. Gallagher also used Ibanez Tube Screamers, an MXR Dyna Comp, and various Boss effects, often using a Flanger and Octaver.

In the early to mid-1970s, Gallagher began to use Fender amplifiers in conjunction with a Hawk booster, most notably a Bassman and a Twin, both 1950s vintage. An example of this sound can be heard on the Irish Tour '74 album. He also had a Fender Concert amplifier.

In the mid to late 1970s, when Gallagher was moving towards a hard rock sound, he experimented with Ampeg VT40 and VT22 amps. He also began using Marshall combos. During this period and beyond, Gallagher used different combinations of amps on stage to achieve more power and to blend the tonal characteristics of different amps including Orange amplification.

On the introduction of the BOSS ME-5 all-in-one floor based FX unit, Rory was known to have been an early adopter and used it readily it for his live work up until his death in mid 90s.

Not that well known is his use of various German amplifiers. He used Stramp 2100a amps, which can be seen in his appearances on the German Beat Club program. Another company that hand built amplifiers for Gallagher was PCL Vintage Amp. The company is located in St. Wendel in the Saarland and they still produce high quality audio and guitar equipment.

According to sources close to Rory, including his brother Donal, Rory developed a great fear of flying as his years progressed. His trust in doctors and medicine, however, was unflagging. Combinations of prescription medication and alcohol use resulted in severe liver damage. Despite this he continued touring. By the time of his final performance on 10 January 1995 in the Netherlands, he was visibly sick and the tour had to be cancelled. Gallagher was admitted to King's College Hospital in London in March 1995, and it was only then that the extent of his ill health became apparent: his liver was failing and a transplant was required. After 13 weeks in intensive care, while waiting to be transferred to a convalescent home, his health suddenly worsened when he contracted a Staphylococcus (MRSA) infection, and he died on 14 June 1995. He was unmarried and had no children.

Gallagher was buried in St Oliver's Cemetery, on the Clash Road just outside Ballincollig near Cork City, Ireland. His headstone is a replica of an award he received in 1972 for International Guitarist of the Year.

In 2003, Wheels Within Wheels, a collection of acoustic tracks, was released posthumously by Gallagher's brother Donal Gallagher. Collaborators on this album included Bert Jansch, Martin Carthy, The Dubliners and Lonnie Donegan.

Many modern day musicians, including The Edge from U2, Slash of Guns N' Roses, Johnny Marr of the Smiths, Davy Knowles, Janick Gers of Iron Maiden, Glenn Tipton of Judas Priest, Vivian Campbell of Def Leppard, Gary Moore and Joe Bonamassa, cite Gallagher as an inspiration in their formative musical years.

Brian May, lead guitarist of Queen, relates: "so these couple of kids come up, who's me and my mate, and say 'How do you get your sound Mr. Gallagher?' and he sits and tells us. So I owe Rory Gallagher my sound." In 2010, Gallagher was ranked #42 on Gibson.com’s List of their Top 50 Guitarists of All Time. Gallagher was also listed on Rolling Stone magazine's list of the 100 Greatest Guitarists of All Time, ranked at 57th place.

the awe that a young Kirwan felt towards Gallagher

and expressing dismay at the loss of such a talent.