The 20-year-old has also spent time with Bray Wanderers on loan.
Athlone moved to address the loss of leading scorer Ronan Manning last night.
First they confirmed the signing of former Wolves academy product Daniel McKenna late last night, for the 2021 season.
The 20 year-old struggled to make an impact for Shels last season, only making the bench for one game and leaving the club in September.
Adrian Carberry wasted no time in picking up his third player of the window, following goalkeeper Michael Schlingermann and McKenna.
A second central midfielder came through the door at Lissywoolen at lunchtime.
Twenty-one year-old Brandon McCann joins the club following a spell with Edenderry Town.
He previously spent time on the books at Shelbourne and most recently was with Bray Wanderers for 18 months up to July of this year.
SIGNING ✍
— Athlone Town AFC (@AthloneTownAFC) December 10, 2020
We are delighted to announce the signing of Brandon McCann!
The 21-year-old central midfielder previously played with Bray Wanderers and is Adrian's third new signing of the off season so far. #ATAFC2021 pic.twitter.com/gjWa4WEVhY