He was selected for the Great Britain national rugby league team squad in 2007, after living in England for 4 years.

He was signed by the then St. Helens coach Ian Millward in the winter of 2003 after a series of outstanding performances playing at flanker for Samoa in the 2003 Rugby World Cup.

Harlequins managed to lure the Great Britain (RL), and Samoan (RU) international back to rugby union.

St Helens reached the 2006 Super League Grand final to be contested against Hull FC, and Fa'asavalu played from the interchange bench in Saints' 26–4 victory.

[11] On 27 October 2007, Fa'asavalu scored on his début for Great Britain against New Zealand in Huddersfield, helping the British team to a 20–14 victory.

Fa'asavalu was selected for the England squad to compete in the 2008 Rugby League World Cup tournament in Australia.