Wagner never led at any point. The Colonials (17-8, 9-3 Northeast Conference) shot 58.3 percent (14 of 24) while building a 42-27 halftime lead, scored five points in the first 9 seconds after halftime and still led 64-53 with 5:45 remaining.
Kenneth Ortiz and Latif Rivers, who each scored 22 points, led the Seahawks (13-10, 7-5). Rivers' layup with 13 seconds left brought them within 72-71. After Jones hit 1 of 2 free throws, Ortiz's layup with 6 seconds left forced overtime.
Two free throws by Jones and a layup by Johnson gave Robert Morris a 77-73 lead, and the Colonials hit all eight of their overtime free throws.
Robert Morris has won nine of its last 10 and clinched its eighth straight winning season.
Authorities say former Michigan State basketball player Keith Appling has been charged with carrying a concealed weapon and other crimes.
Point guard Jaylen Fisher, who reopened his recruitment after coaching changes at UNLV, has committed to TCU over a long list of schools.
Forward Kennedy Meeks, who has averaged 9.4 points and 6.5 rebounds at North Carolina, has pulled out of the NBA draft and will return to the Tar Heels.