His competitive debut for Celtic came on 3 September 1955 in a Scottish League Cup tie against Falkirk and this first season would end with a maiden Senior final appearance, Celtic losing 3–1 to Hearts in the Scottish Cup. It was in the League Cup however that Beattie would enjoy his greatest success. Victory over Partick Thistle after a replay in the 1956 Scottish League Cup Final earned him his first winners medal. The following season saw a career highlight as Celtic defeated city rivals Rangers, 7–1 in the 1957 Scottish League Cup Final.
