Aksalu joined the youth system of his hometown club Kuressaare and played for their reserve team Muhumaa (renamed Sörve in 2002).

On 29 January 2010, following a successful trial, Aksalu signed a two-and-a-half-year contract with Championship club Sheffield United for a transfer fee of £180,000.

On 6 October 2010, Aksalu joined Conference National club Mansfield Town on a two-month loan.

[4][5] He remained sidelined through most of his spell due to an abdominal muscle problem, making only three appearances before returning to Bramall Lane in December.

On 24 September 2016, Aksalu helped his team win the 2016 Finnish Cup by saving two penalties in a shootout against HJK in the final.

[14] He made his senior international debut for Estonia on 17 October 2007, playing the first half of a friendly match against Montenegro, where he conceded the only goal of the game.