Dos Anjos replaces Evan Dunham, who suffered an undisclosed injury that forced him to withdraw from the bout.
Both are former Fight of the Night winners, while dos Anjos won Submission of the Night once.
"I expect an amazing fight," UFC president Dana White said.
However, both are coming off losses. Dos Anjos was submitted by Clay Guida on Aug. 7, 2010, at UFC 117. Before the setback, dos Anjos (14-5-0) had won three in a row.
The once highly touted Sotiropoulos (14-3-0) lost a unanimous decision against Dennis Siver in February.
Heading into the bout with Siver at UFC 127, Sotiropoulos had put together an eight-fight win streak.
Franklin McNeil covers mixed martial arts and boxing for ESPN.com. Follow him on Twitter at www.twitter.com/Franklin_McNeil.