Director Bryan Singer made the announcement about Till's return on social media, said The Hollywood Reporter.
Till, 24, made his X-universe debut in 2011's "X-Men: First Class" and appeared in last summer's "X-Men: Days of Future Past".
Apocalypse will showcase a mix of the old and new actors. Returning to the franchise are Michael Fassbender, Jennifer Lawrence, James McAvoy and Nicholas Hoult, who are reprising their characters from the previous two movies.
Among the new faces are Tye Sheridan as a young Cyclops, Kodi Smit-McPhee as Nightcrawler, Oscar Isaac as the villain Apocalypse and Olivia Munn as Psylocke.