The change comes on the heels of an injury that forced Karlos Vemola off the card.
UFC officials announced the matchup earlier today.
UFC 155 is set to take place on Dec. 29 from the MGM Grand Garden Arena in Las Vegas. In the main event UFC heavyweight champion Junior dos Santos will defend his title in a rematch against former champ, Cain Velasquez.
Brunson makes his UFC debut on the heels of back-to-back losses against Jacare Souza and Kendall Grove.