Gilmour has been sidelined since July after suffering a knee injury during a pre-season match against Crystal Palace.
It was a setback for the 19-year-old after a breakthrough season under Frank Lampard which saw him make 11 first-team appearances.
Gilmour had a brief cameo for Scotland Under-21s, which saw him sent off after coming on as a substitute, and got more minutes in the EFL Trophy defeat at Bristol Rovers in midweek.
The midfielder started and scored on Sunday as Chelsea's development squad came from 2-0 down to draw with Manchester City in Premier League 2.
Gilmour found the net from 18 yards after latching onto George Nunn's pass. Myles Peart-Harris then found the equaliser.
"He is fit again," Lampard said of Gilmour ahead of the weekend. "He played on Wednesday night in the EFL Trophy, got good minutes and I’ve heard he played well so we are happy with him and he’ll play again at the weekend in the Under-23s.
"He’s getting minutes but he’s not match fit. That will be a short period as he is a generally fit boy. I’m really excited to have him back fit."
This weekend get a £10 free bet with Betfair, when you bet £10 on a Same Game Multi on the Premier League.
Terms: Min £10 Same Game Multi bet on any EPL match this Fri - Sun. Free bet valid for 72 hours, awarded at bet settlement. Excludes cashed out bets. T&Cs apply.