A Manawatu representative, Whakarau moved south in 1986, joining the Upper Hutt Tigers and played till the 1991 season Wellington Rugby League and becoming a Wellington representative.
Sonny first went to the UK in 1991 and played for Batley Rugby League club, he then got signed by Bramley Rugby League club by former Great Britain Rugby League coach Maurice Bamford and had two successful seasons there in 1992 and 1993, In the 1994/1995 English season Whakarau joined Doncaster and helped them win promotion to the First Division under the coaching of former Welsh and Great Britain hard man Tony Fisher.
[4] Whakarau represented New Zealand Māori at the 1996 Pacific Cup and then played in their defeats of Papua New Guinea and Great Britain the same year.
[10] In 2004 Whakarau played for the Levin Lions in the Western Alliance club competition.
[11] Whakarau was selected for New Zealand Māori as part of the 2004 Pacific Cup squad.