He made his first-class debut for Central Districts in the 1958-59 season aged only 17, and played all four matches for New Zealand in the non-Test series against an Australian XI in the following season. Wisden described him as "the real discovery of the season". The Australian captain, Ian Craig, described facing him in the first match of the series in Wellington: "I saw Bartlett let go of the ball, but the first I knew of where it had gone was the sound of it hitting the gloves yards behind me. I think it was the quickest bowling I faced." Bartlett moved to Canterbury for the 1963–64 season where he was a member of the Burnside West Christchurch University Cricket Club then returned to Central Districts in 1966–67. He played his last first-class matches in the 1969–70 season. He also played for Marlborough in the Hawke Cup; in his first match, against Waikato in 1957–58, aged 16, he took 6 for 37 and 2 for 11 and hit the match top score of 52 not out.
International career
He toured South Africa in 1961-62, making his Test debut and playing all five Tests. He took only eight wickets but made useful runs batting at eight or nine. He made only occasional Test appearances thereafter, all in New Zealand. His outstanding Test moment came in the Second Test against India in Christchurch in 1967–68, when he took 6 for 38 – at the time the best figures in Tests by a New Zealand bowler – in the second innings to help New Zealand to its first victory over India. Unfortunately this success, and much of his career, was overshadowed by doubts about the legitimacy of his bowling action. During the Christchurch Test the Indian bowler Syed Abid Ali protested against Bartlett's action by blatantly throwing the ball himself. Bartlett missed the next Test, but when he was selected for the Fourth Test, the Indian manager, Ghulam Ahmed, protested. According to the Nawab of Pataudi, "All the Indian players, including myself, considered Bartlett's action to be suspect." Despite the doubts and accusations, Bartlett was never no-balled for throwing.