Poirier (13-2) replaces Dennis Siver. UFC has not yet disclosed the reason for Siver's removal from the event, which will air on Fuel TV.
In his most recent outing, Poirier (ranked sixth among 145-pound fighters by ESPN.com) defeated Jonathan Brookins by first-round submission. The fight was held on Dec. 15 in Las Vegas.
Before his win over Brookins, Poirier has a five-fight win streak snapped by Chan Sung Jung. Poirier lost that fight on May 15 by fourth-round submission.
The ninth-ranked Swanson has won three fights in a row. He knocked out Charles Oliveira in the first round at UFC 152, improving his professional record to 18-5.