Jimmy Thunder turned pro in 1988, after being omitted from New Zealand's Seoul Olympic Games team. He changed his surname from Peau to Thunder in 1989 at the suggestion of his manager at the time, Jack Rennie. Later in his professional career he also fought under the name James Thunder.Among his notable victories are wins over Tony Tubbs, Craig Peterson, Trevor Berbick, and Tim Witherspoon. On the 18 March 1997 edition of the USA Network's Tuesday Night Fights he knocked out Crawford Grimsley with his first punch, scoring the fastest knockout in history at 13 seconds, including the count of 10, which was not even begun, so it lasted 3 seconds, during the quick walk from his corner to the ring centre, immediately throwing the first and only punch with his last step. He finished his 49 fight career with 35 victories, 28 by knockout. Throughout his career he won regional titles including the Australian Heavyweight Champion twice as well as winning the lesser IBO and WBF Heavyweight titles.

Derek Williams....................................Fight #12

Craig Petersen I..................................Fight #14

Craig Petersen II.................................Fight #16

Melton Bowen.....................................Fight #20

Ramon Perez (rare)............................Fight #24

Marion Wilson (rare)..........................Fight #25

Ed Donaldson......................................Fight #26

Richard Mason....................................Fight #27

Tony Tubbs...........................................Fight #28

Trevor Berbick.....................................Fight #29

Daniel Dăncuță....................................Fight #30

Bomani Parker......................................Fight #31

Franco Wanyama................................Fight #32

Ray Anis.................................................Fight #33

Melvin Foster........................................Fight #34

Will Hinton.............................................Fight #35

William Morris......................................Fight #36

Quinn Navarre......................................Fight #37

John Ruiz...............................................Fight #38

Crawford Grimsley...............................Fight #39

Maurice Harris......................................Fight #40

Chris Byrd..............................................Fight #41

Tim Witherspoon.................................Fight #42