He made his debut for the Kerry seniors in the 2007 National Football League, coming on as a substitute wing-forward on 11 March against Limerick.

In 2008, Walsh was selected in the team for the first game of the All-Ireland Senior Football Championship following some impressive NFL performances in the full-forward line.

[6] Players' agent Ricky Nixon described it as a 'big coup' for the AFL and said '"I can’t tell you if he'll want to play or stay or if he’ll be good enough but he’s definitely one of the best talents that I’ve seen.

"[6] However, Walsh later withdrew from the original trial and did not travel to Australia before the recruitment deadline, although he accepted an invitation to spend some time training with St Kilda.

Kerry came through the qualifiers to meet Dublin in the All-Ireland quarter-final, but Walsh was not on top form and was replaced before half-time.

[citation needed] In the 2009 All-Ireland Senior Football Championship Final, in which Kerry overcame Cork, Walsh notched up four points from play (two with each foot).

In October 2011, Walsh requested and received a trade to the Sydney Swans and was selected for Ireland for the 2011 International Rules Series against Australia.

Walsh made his senior debut on Saturday 19 May 2012 against Melbourne,[12] kicking two goals as the Swans won by 101 points.