Cejas joined the Racing Club youth team in 1959 at the age of 13. He made his first team debut in 1962 at the age of 17. In 1966, he helped Racing Club to win the Argentine Primera. The following year Racing won the Copa Libertadores 1967 to become Libertadores champions of South America for the only time in the clubs history. They followed this up by beating Celtic F.C. in the Copa Intercontinental to become the first Argentine club champions of the world.
In 1977, Cejas returned to Racing Club where he played until 1980. By the end of his second period with the club he had set a club record of 313 appearances. He then had a short spell with River Plate where he was part of the squad that won the Nacional in 1981.