Cowdell turned pro in 1977 and in 1981 took on WBC world featherweight champion Salvador Sánchez, losing a close and hard-fought split decision in which Cowdell was dropped in round 15. In 1985 Cowdell challenged Azumah Nelson for the WBC featherweight title, but was caught cold by a bullet of a punch and knocked out in the first round.
In 1977, Cowdell turned professional boxing.  He fought Salvador Sánchez for the WBC featherweight championship in 1981, losing a close fight with a split decision after being knocked down in round 15. In 1985, he challenged Azumah Nelson for the WBC featherweight title but was knocked out in the first round after being hit by a powerful punch.