Celtic signed Lennox from
Scottish Junior team Ardeer Recreation on provisional forms in 1961 at the age of 18, and he made his first team debut the following March. He went on to score 301 goals in all competitions, second only to Celtic's all-time top scorer
Jimmy McGrory's total of 468 goals. Of those, 171 were scored in the
Scottish league, making him the fifth-highest league scorer for Celtic. He placed third for the
European Golden Boot in 1967–68. He won 11 League medals, eight
Scottish Cup medals, and five
League Cup medals (scoring 63 goals in the competition) and was a member of the 1967 European Cup-winning Celtic team, the
Lisbon Lions, who defeated
Inter Milan 2–1 in the
Estádio Nacional stadium in
Lisbon, Portugal. He played in a second European Cup final with Celtic in 1970, losing 2–1 after
extra time to
Feyenoord Rotterdam of the Netherlands at the
San Siro stadium,
Milan. He was an extremely fast winger and was known by fans as 'Buzz Bomb' or 'Lemon' as they thought he made defenders look like 'suckers'. He left Celtic in March 1978, and moved to the United States to play for
Houston Hurricane in their debut season in the
NASL. After a disappointing three goals in 30 games for a struggling team, he got a surprise offer to rejoin Celtic in September 1978. It was a good move, as Celtic took the League Championship that year and the Scottish Cup in 1980. He was the last Lisbon Lion to retire as a player when he joined Celtic's coaching staff in November 1980. ==International career==