Antonio headed home in the dying moments to earn a share of the spoils after Daryl Murphy's double had sandwiched Robert Tesche's initial leveller.
Forest, who sit second in the Championship behind Norwich City, began like a team with confidence, Matty Fryatt heading Antonio's cross against the woodwork.
Ipswich grew into the game with Murphy hitting just over the crossbar from a tight angle.
The striker made no mistake when his next chance came, cutting inside and hitting a low effort into the net.
Forest came out firing after the break and Dean Gerken had to produce a stunning save to deny Antonio.
The leveller eventually came midway through the second half, Tesche heading Henri Lansbury's corner home at the back post.
Ipswich found a perfect response when Murphy superbly headed beyond Gerken to seemingly secure the spoils.
There was to be a twist in the tale, however, Antonio popping up at the back post to leave Ipswich sixth, four places behind their opponents.
