Kucinich voted against the House version of the healthcare bill in 2009 and has criticized the Senate version as being worse than its counterpart in the lower chamber.
Kucinich said he would vote yes, despite his misgivings, framing his decision as one of not wanting to be the deciding vote against healthcare reform, The Hill reported.
"In the past week, it's been clear that the next vote on healthcare will be quite close," Kucinich said. "This is a defining moment ... to move off square one."
His vote, he said, would "not (be) on the bill as I would like to see it, but as it is."
Kucinich's announcement came two days after President Barack Obama campaigned on healthcare in Ohio.
Obama's visit to his district underscored "the urgency of this moment," Kucinich said.
Kucinich is the first "no" vote from the November action to commit publicly to voting yes.