Peltier missed Saturday's game after he picked up his fifth yellow card of the season against Hull City. Boro are struggling for numbers at the back, with Warnock delighted to have right-back Peltier available again.
“There are a few niggles and a few haven’t trained yet but I’m still hoping we have the same group,” said Warnock.
“We just have to look after people with having three games in the space of a week. With Sol Bamba being the only defender, it’s been strange really.
“I think the way Barnsley play will be more of a test for the lads at the back, so it’s nice to have Lee available.”
With the lack of options in defence, Warnock was forced to deploy some of his players in unfamiliar positions on Saturday.
He added: “We had plenty out of position on Saturday, but all credit to them. They approached it the right way and I think we deserved the win."