The 27-year-old hasn't played since February under new Hibs boss Colin Calderwood, but is now hoping to show what he is capable of at Tannadice.
"I'm a Dundee United player now and I'm desperate to get in about the football and know where I'm going," said Rankin.
"You work yourself into the ground every day and you feel as if you deserve a chance on a Saturday.
"But you're just not that manager's cup of tea. Even though you've been playing every game under the previous manager.
"For whatever reason, they just don't fancy you. That's what happened to me at Hibs. Colin Calderwood came in and put his own stamp on the team, doing everything the way he wants to.
"I didn't want to go through the summer not knowing what was giong to be happening - I wanted it sorted as soon as possible."