Officials confirmed the 155-pound bout with ESPN.com on Tuesday, following an initial report by MMAFighting.com. A flyweight title bout between Magomed Bibulatov and Donavon Frelow has also been scheduled for the WSOF 24 televised event.
Born with a partially developed left arm, Newell (12-1) has compiled a 3-1 record in WSOF, including two wins via submission. His only professional loss came at the hands of current champion Justin Gaethje in July 2014.
Newell, 29, rebounded from that loss with a three-round decision over Joe Condon in April. Eight of Newell's 12 professional wins have ended in submissions.
Marcellino (7-3) signed with WSOF last year. He suffered a unanimous decision loss to Frankie Perez in his promotional debut in September.