The visitors took a surprise lead through Kasper Hamalainen in Brussels, but Lukaku came off the bench to ensure that the number two ranked national team in the world at least avoided defeat.
Much of Belgium's attacking threat in the first half came from Jan Vertonghen, though, with the Tottenham Hotspur defender testing Lukas Hradecky on a couple of occasions, including one free kick that brought a fine stop from the visiting keeper.
Hradecky was by far the busier of the two shot-stoppers in the opening 45 minutes, and he was called into action again towards the end of the half to deny Marouane Fellaini's powerful header from De Bruyne's corner.
Belgium did finally find a way past the keeper with five minutes of the half remaining, but this time the woodwork came to Finland's rescue as Batshuayi's header came back off the upright.
Batshuayi sent another header off target five minutes into the second half, but despite Belgium's dominance it was Finland who took the lead shortly afterwards when Hamalainen scored against the run of play.
The hosts were straight back on the offensive, though, and began to pepper the Finland goal with shots around the hour mark as Toby Alderweireld, Dries Mertens and Fellaini all came close on a couple of occasions each.
Christian Benteke was the next to threaten with just over 15 minutes remaining, but the Liverpool striker failed to level things up having been found by Vertonghen at the back post.
Belgium did finally restore parity in the final minute of normal time, though, as Lukaku rescued a draw with his 14th goal for his country to make it just one defeat in eight games for the Red Devils.
Marc Wilmots's side will next face Norway in their final warm-up game on Sunday before beginning their Euro 2016 campaign against Italy on June 13.