A right-handed batsman and right-arm off-break bowler,[1] Millett played for Cheshire from 1949 to 1972, captaining them from 1960 to 1970.[2] In 210 Minor Counties Championship matches, he scored 8432 runs and took 300 wickets.[2]
He also played seven first-class matches for the Minor Counties combined side against various touring Test teams.[3] His best score in these matches was an unbeaten innings of 102 against the West Indies in 1969, a match in which he was also captain.[2]
He played twelve List A matches, four of which were for Cheshire in the Gillette Cup, the remainder for a Minor Counties North team in the Benson & Hedges Cup.[4]
After he finished playing for Cheshire, Millett served on the Marylebone Cricket Club's cricket committee, serving as player manager on a tour to the U.S. in 1982.[2] He also played for the MCC in several minor matches against Ireland and Scotland.[5]