Lukaku is to remain at the Hawthorns for the rest of the season after Chelsea decided not to take up an option to recall him this month.
The 19-year-old, who recently indicated he wants to return to Albion for another season in 2013-14, has begun to force his way into the starting line-up in recent weeks.
He has already netted seven times and overhauled Shane Long to become Albion's current top-scorer for this campaign.
Brunt said: "Romelu has been confirmed as staying here for the season which is great news. He's come into his own during the last month.
"The gaffer has been chopping and changing him and Shane (Long), and Rom has stepped up and grabbed a few goals for us.
"He's been consistently hitting the net in the last few weeks, even when we've not played that well, and the more he plays, the better and better he'll get."
Brunt added: "People forget Rom is only a young lad, he's still learning the game but he's a real handful.
"He gets into good areas and hopefully he'll put more and more chances away as he gets more football."
Meanwhile, winger Jerome Thomas is hoping to convince manager Steve Clarke he has a future at Albion after returning from a loan spell at Leeds.
Thomas, whose current deal runs out this summer, said: "Maybe now this is my chance to show the gaffer and management what I can do.
"I'm happy here, I've been playing here for a few years and have no plans to move on. Hopefully I can get something resolved."