[6] His performances attracted the attention of several rugby league clubs, including Wakefield Trinity, Hull FC, Huddersfield and Wigan.

[8] In June 1921, Sullivan turned professional and joined rugby league side Wigan, reportedly signing a 12-year contract for a fee of £750.

Jim Sullivan played fullback, and scored 4-conversions in Wigan's 13-2 victory over Oldham in the Championship Final during the 1921–22 season at The Cliff, Broughton on Saturday 6 May 1922,[9] played fullback, and scored 4-conversions in the 22-10 victory over Warrington in the Championship Final during the 1925–26 season at Knowsley Road, St. Helens on Saturday 8 May 1926.

[17] During the Second World War, he played infrequently for Wigan, as he chose to appear as a guest for a number of other clubs, including Dewsbury, Keighley and Bradford Northern.

[19] Having been captain-coach at Wigan since 1932, Sullivan continued managing the team after retiring as a player in 1946, creating one of the club's greatest sides by winning a record five championships and a brace of Challenge Cups.

[2] Sullivan was the coach in Wigan's 8-3 victory over Bradford Northern in the 1948–49 Challenge Cup Final at Wembley Stadium, London on Saturday 1 May 1948, in front of a crowd of 91,465.

Sullivan was the coach in St. Helens' 10–15 defeat by Huddersfield in the 1952-53 Challenge Cup Final at Wembley Stadium, London on Saturday 25 April 1953, in front of a crowd of 89,588,[21] and was the coach in the 13-2 victory over Halifax in the 1955–56 Challenge Cup Final at Wembley Stadium, London on Saturday 28 April 1956, in front of a crowd of 79,341.

Sullivan was the coach in St. Helens' 44–22 victory over Hunslet in the Championship Final during the 1958–59 season at Odsal Stadium, Bradford on Saturday 16 May 1959.