Walker played for several NRL clubs including the St George Dragons, Sydney Roosters and the Manly-Warringah Sea Eagles.

He is known as the first dual-international to switch codes from league to union; 2 years before the more publicised exodus of Wendell Sailor and Mat Rogers.

However his debut was not a memorable one as he came off the bench for the last 10 minutes of the game at Stadium Australia in front of a world-record crowd and proceeded to miss a conversion, kick straight down the throat of Christian Cullen and then, after the resulting New Zealand try to Jonah Lomu to win them the game 39–35, he failed to send the kick-off 10 metres and New Zealand received the ball.

[5] In 2006 he resurrected his career by signing to play with French rugby union club UA Gaillac.

[6] In early March, Walker was named on the bench of the Queensland Reds team and played the last 15 minutes in their Week 5 defeat by the Lions.