Ngamu started his career at the Marist Saints and Northcote Tigers in the Auckland Rugby League competition.
[3] He joined the Tigers in the 1992 pre-season while on a scholarship with the Manly-Warringah Sea Eagles, however was called to Sydney full-time before the season began.
A goalkicker, Ngamu holds the record for Most Points in a Match for the Auckland Warriors, a feat only equaled by Ivan Cleary and James Maloney.
Ngamu was selected for the New Zealand team to compete in the end of season 1999 Rugby League Tri-Nations tournament.
[6] Ngamu made his international début for the New Zealand national rugby league team in 1993, one year after his Junior Kiwis debut.