Pickett (25-11) is coming off a February split decision win over Francisco Rivera that snapped a three-fight losing streak for the Brit. The soon-to-be 38-year-old is 5-5 over his last 10, including losses to Thomas Almeida, Ian McCall and Michael McDonald.
Alcantara (33-7) is two years removed from a three-fight win streak and a record of 5-2 with one no-contest during a stretch of action inside the Octagon. Last January, he lost to Jimmie Rivera.
UFC 204 takes place October 8 from Manchester, England and features Michael Bisping defending his middleweight title against Dan Henderson.