The 20-year-old has already made nineteen appearances and scored 3 goals for The Shots this season, after joining on loan in August 2017, but was recalled by Ipswich manager Mick McCarthy in December.
A former Republic of Ireland under-19 international, McDonnell previously made three appearances for Ipswich Town’s first-team in 2017/18, including playing the full 90 minutes of August’s Carabao Cup tie against Crystal Palace.
He has also made two substitute appearances in the Championship this season, to add to two starts made in the 2015/16 season.
Born in Dunboyne, near Dublin, McDonnell graduated from the schoolboy section of League of Ireland side Shelbourne before joining Ipswich in August 2014, and then signed a new two-year contract at Portman Road in July 2016.
“Being here has made me a better player and will help me fulfil my potential,” McDonnell told the club`s press office Steve Gibbs. “Gary Waddock and James Rowe have put a lot of trust in me, and with the way that we play I’d be stupid not to come back here.
“I wasn’t being promised the game time that I needed at Ipswich Town to make me a better player, so sometimes you have to come down to go back up. At this club, that will definitely make me a better player.
“Everything about the club has been brilliant for me. The players made me fit in from minute one, the staff, the fans, and obviously I love playing at the EBB Stadium.”
McDonnell is the fourth signing to be made with assistance from Aldershot’s `500 Club`, which saw supporters donate funds to Waddock’s playing budget in a unique ‘money-back-and-more’ incentive on helping push The Shots to promotion back to the Football League.