Born in Liverpool, Merseyside, England, Byrne, like Jimmy Melia, joined Liverpool straight from school as a 15 year old in 1953, again like Melia, Byrne impressed manager Don Welsh who offered the full-back a professional contract the day after his 17th birthday on 30 August 1955. It was just over two years later that Byrne mad his debut, it was a day to forget for Byrne as Charlton Athletic thrashed the Reds 5-1 in a league match at The Valley on the 28 September 1957, he had to wait a further 4½ years for his first goal which came in the 52nd minute of a 3-1 2nd Division win over Brighton at Anfield on 3 February 1962.
His debut was his only appearance during the 1957–58 season and it wasn't until the arrival of Bill Shankly that he really got his chance; he featured in 38 league and cup matches as the Reds finished third for the fifth time in a row in the second division. Considering he only played seven times in the previous three seasons this was a major improvement in Gerry's career; in-fact he was on the transfer list when Shankly arrived, soon to be removed.
Shankly again used Byrne's grit and determination to its fullest, he was an ever-present as Liverpool, finally, romped to the 2nd division title, beating Leyton Orient into second spot by eight points.
Gerry played in 38 of Liverpool's 42 league games their first year back in the big time and he also played in all seven of Liverpool's cup ties during their run to the 1965 FA Cup final, a game in which Byrne would write his name in Liverpool folklore forever more.
Gerry Byrne will always be remembered for playing for Liverpool in the 1965 FA Cup Final, which took place on the 1 May at Wembley with a broken collarbone. He suffered the injury as early as the third minute, but played on throughout the rest of the game and the whole of extra-time as Liverpool won the Cup for the very first time. The break happened after Byrne was challenged heftily by Leeds United's captain Bobby Collins, but, with substitutes still not permitted by the authorities in 1965, he had little choice but to carry on playing. He and his team-mates, not to mention Shankly and his coaching team on the Liverpool bench, somehow managed to keep the extent of Byrne's injury a secret from the Leeds United players and staff.
Unfortunately for Byrne the game went to extra-time and Gerry, despite the agonising pain, kept making his familiar marauding runs down the left flank in joining the attack. Early on into the first period of extra time, he reached the by-line with the ball and pulled back a perfect cross for Roger Hunt to open the scoring. Leeds got back into the game and equalised through Billy Bremner but Liverpool were not to be denied as Ian St. John headed home the winner late on during the second period and Liverpool had finally won their first ever FA Cup. Shankly spoke highly of Gerry in an interview after the final saying "It was a performance of raw courage from the boy", high praise from a man who appreciated such endeavour.
The aftermath of another high profile match led to calls, again, for the Football Association to allow a substitute to be selected by each team in competitive matches. In FA Cup finals over the previous decade, there had been a notable amount of teams reduced to ten men or hampered considerably by hard, spiteful or accidental challenges from opposition players, including two goalkeepers suffering a broken neck (Bert Trautmann, 1955) and broken cheekbone (Ray Wood, 1957) respectively; two wingers in successive years being stretchered off with broken legs (Roy Dwight, 1959 and Dave Whelan, 1960) and a full back left hobbling for three quarters of the game with a damaged ankle (Len Chalmers, 1961). Byrne's injury was the latest to try to force the FA's hand and, eventually, two years later the first substitutes were allowed in the FA Cup final.
Shankly was a Master tactician and player of mind games, which lead him to pull off a masterstroke just before the Semi-final of the European Cup against Inter Milan, Anfield was already buzzing in anticipation of the up and coming game when Shankly sent out the injured pair of Gerry Byrne and his full-back partner Gordon Milne with the piece of silverware the Koppites had dreamt about for decades, the FA Cup, the crowd erupted and, it's said, you could see the Italian champions freeze on the spot, it had the desired effect as Liverpool ran out comfortable 3-1 winners. However, the 2nd leg at the San Siro was full of controversy as Internazionale got a 3-0 win to end Liverpool's dreams of a cup double.
The 1965–66 campaign was another triumphant one for Byrne and the Reds as he was an ever-present in Liverpool's second title win in three years, Shankly's Reds were now the team he said he was always going to put together, tough, hard to beat whilst playing flowing football, all three were attributes Byrne had in abundance. Byrne, along with the elegant winger Ian Callaghan and the prolific Hunt were rewarded for their superb club form by being selected in Alf Ramsey's England squad for the 1966 World Cup finals to be held on home soil; unfortunately both Byrne and Callaghan didn't feature in any of the matches but the honour of actually being a squad member for the World Champions is immense.
Byrne eventually won two international caps for England earning his debut on 6 April 1963 at Wembley against Scotland, the Scots took the spoils 2–1 in a game which saw fellow Liverpool team-mate Jimmy Melia make his England debut.
Gerry stayed on at Anfield until 1969 when injury drew the curtains on his outstanding career, a rock at left-back; he and right-back Geoff Strong formed a partnership that bred fear into wingers up and down England and Europe too, especially in 1965 when the Reds reached the European Cup semi-finals. Byrne was replaced by yet another in the long line of excellent left-backs Alec Lindsay.