Hartlepool United sign former Fulham defender
The 20-year-old has been on trial at Pools over the summer, with the club now agreeing a deal to make him a permanent fixture in Craig Hignett's squad.
Donnelly - who spent the last four years with Fulham - is most comfortable in the centre of defence or at right-back but did operate in a holding midfield role on occasions during pre-season.
The Dungannon-born Northern Ireland Under-21 international has been handed squad number 33.
"Tommy Miller had seen him playing for Fulham and recommended him so we brought him up to have a look," said Hignett.
"He’s a competitive lad who can play in a variety of positions so that versatility was vital and he really impressed us during the games he played and in training.
"Liam is still young and he’s keen to learn and improve so he’s just the type of character we’ve looked to bring in – players who have a point to prove and are hungry."