In 1967, Pink Floyd began to attract the attention of the music industry. While in negotiations with record companies, IT co-founder and UFO club manager Joe Boyd and Pink Floyd's booking agent Bryan Morrison arranged and funded a recording session at Sound Techniques in West Hampstead. Three days later, Pink Floyd signed with EMI, receiving a £5,000 advance
EMI released the band's first single, "Arnold Layne", with the B-side "Candy and a Currant Bun", on 10 March 1967 on its Columbia label. Both tracks were recorded on 29 January 1967.
"Arnold Layne"'s references to cross-dressing led to a ban by several radio stations; however, creative manipulation by the retailers who supplied sales figures to the music business meant that the single peaked in the UK at number 20.


EMI-Columbia released Pink Floyd's second single, "See Emily Play", on 16 June 1967. It fared slightly better than "Arnold Layne", peaking at number 6 in the UK.[ The band performed on the BBC's Look of the Week, where Waters and Barrett, erudite and engaging, faced tough questioning from Hans Keller. They appeared on the BBC's Top of the Pops, a popular programme that controversially required artists to mime their singing and playing. Though Pink Floyd returned for two more performances, by the third, Barrett had begun to unravel, and around this time the band first noticed significant changes in his behaviour. By early 1967, he was regularly using LSD, and Mason described him as "completely distanced from everything going on".
EMI-Columbia released The Piper at the Gates of Dawn in August 1967. The album peaked at number 6, spending 14 weeks on the UK charts. One month later, it was released under the Tower Records label. Pink Floyd continued to draw large crowds at the UFO Club; however, Barrett's mental breakdown was by then causing serious concern. The group initially hoped that his erratic behaviour would be a passing phase, but some were less optimistic, including Jenner and his assistant, June Child, who commented: "I found [Barrett] in the dressing room and he was so ... gone. Roger Waters and I got him on his feet, [and] we got him out to the stage ... The band started to play and Syd just stood there. He had his guitar around his neck and his arms just hanging down".
In December 1967, reaching a crisis point with Barrett, Pink Floyd added guitarist David Gilmour as the fifth member. Gilmour already knew Barrett, having studied with him at Cambridge Tech in the early 1960s. The two had performed at lunchtimes together with guitars and harmonicas, and later hitch-hiked and busked their way around the south of France.
Steve O'Rourke, set Gilmour up in a room at O'Rourke's house with a salary of £30 per week , and in January 1968, Blackhill Enterprises announced Gilmour as the band's newest member, intending to continue with Barrett as a nonperforming songwriter.
According to Jenner, the group planned that Gilmour would "cover for [Barrett's] eccentricities". When this proved unworkable, "Syd was just going to write. Just to try to keep him involved
Working with Barrett eventually proved too difficult, and matters came to a conclusion in January while en route to a performance in Southampton when a band member asked if they should collect Barrett. According to Gilmour, the answer was "Nah, let's not bother", signalling the end of Barrett's tenure with Pink Floyd.
In 1968, Pink Floyd returned to Abbey Road Studios to record their second album, A Saucerful of Secrets. The album included Barrett's final contribution to their discography, "Jugband Blues". Waters began to develop his own songwriting, contributing "Set the Controls for the Heart of the Sun", "Let There Be More Light" and "Corporal Clegg".
Pink Floyd toured extensively across America and Europe in 1970.