University officials announced Kirk's decision Friday and said no news conference was planned as Kirk will release a statement through his agent on Saturday.
They said Kirk will graduate next month with a degree in marketing.
A 22-year-old Los Alamos native, Kirk ranks eighth in school history in rebounds with 685 and fourth in blocked shots with 168.
Kirk averaged 13 points, eight rebounds and nearly three blocks per game this season for the Lobos.
New Mexico had a 27-7 record, including a 15-3 mark in the Mountain West, and made it to the NCAA tournament under first-year head coach Craig Neal.
''We are fully supportive of Alex and his decision and will do everything we can to help him,'' Neal said. ''I recruited Alex since he was a sophomore in high school and I have been able to work with him and watch his development.''