O’Reilly made his league debut for Shrewsbury at the start of last term – one of 12 appearances he made in League One during his six-month loan.
He went back out on loan during January to MK Dons for the rest of that campaign, which brought 16 more league outings, including three starts, and his first senior goal.
O’Reilly says he took his time to decide the best club to join this season and is very happy that things are working out under Alex boss Lee Bell.
“It was an important decision for me because I’ve had a few loans,” he said.
“I wouldn’t say they were bad, I’d say I’ve had to learn from them and hopefully this loan will be good for me.
“It was really important I chose a team that would suit me football-wise and I think it’s shown that when I’ve got that I can deliver the goods.
“My aim was to come here and play as many games as I can and the gaffer’s helping me do that by putting me in the team and trusting me to play.
“Hopefully I can keep repaying him and the fans and show them I’m good enough to be in the team.”
Eighth-placed Crewe go to Oldham on Saturday hoping to make it three wins in a row in League Two as they try to close the four-point gap to leaders Walsall.