The Central Coast Mariners midfielder has attracted interest from QPR and Reading but has spent the last week training with Celtic in Marbella.
Neil Lennon has been impressed by the 20-year-old with a fee in the region of €550,000 agreed between the two clubs.
Celtic were set to return from Spain today with assistant manager Johan Mjallby happy with the new addition.
After last night's 2-1 win over Steaua Bucharest he said: "It is great news Tom is coming back with us and hopefully we will get the deal done. He has been really impressive in training and you can see he has real ability.
"I'm sure Tom watched the games against Barcelona and realised playing for Celtic in the Champions League is second to none.
"It is great for him, too, as Celtic is a team full of young talents who are looking to improve and have great careers. Celtic is a great place for Tom to start in European football."
Georgios Samaras and Mo Bangura scored against Steaua with Anthony Stokes getting a 20-minute run out after being sidelined by injury.