Jake Kretzer came off the bench to score 13 and was one of five players with multiple treys for the Zips (9-2). Johnson, who was 7 of 9 from the field, had 10 rebounds as Akron had a 38-30 advantage on the boards.
Jordan Washington had 21 points and Jahaad Proctor 18 to lead the Gaels (4-6).
Washington had 15 points off the bench and Iona shot 54 percent in the first half but trailed 41-39. The Gaels cooled to 36 percent in the second half, going just 2 of 11 from 3-point range, while the Zips shot 54 percent to pull away.
Akron opened the second half with a 12-2 to push the lead to a dozen and made it a 17-point lead late after a McAdams 3 and a dunk.