Jim Creeggan has played the double bass since he was in school. He was a member of a variety of school bands, as well as local youth symphony groups. He also attended the University of Toronto for bass performance, though he did not complete a degree. Creeggan, along with his brother Andy, was invited to play with Ed Robertson and Steven Page (then performing as Barenaked Ladies as a duo) at a Christmastime show in Toronto, and the pair was asked to join the band permanently. Creeggan has been with the band ever since, while his brother left the band in 1995. He and Andy formed a group together named The Brothers Creeggan before Andy left BNL. They continued to play following his departure, and went on a hiatus in the early 2000s.

He regularly plays a double bass, both bowed and pizzicato. He has also played Electric double bass (including a Zeta bass circa Maybe You Should Drive, and a couple Ned Steinbergers later on), and bass guitar for BNL. He won the 1999 best male bassist award from the Gibson Guitar Corporation. He uses a French bow for his double bass. He has occasionally played guitar on some Barenaked Ladies songs; mainly on songs which he sings lead (though he also plays bass on some of those). Creeggan has also contributed to albums with each of the other members of the violin family, and has orchestrated musical charts for various band instruments to be recorded by session musicians.

Creeggan has played bass as a guest on a number of albums; mostly of Canadian artists. He also commonly joins artists opening for Barenaked Ladies who do not play with a full band. He has done this on the band’s Ships and Dip cruises as well.