Green Bay finishes the season 21-17, breaking the single season program records for both total points (3,090) and 3-pointers made (303).
The Phoenix led 42-40 at halftime, but Marshall (23-14) poured in 50 points in the second. The Herd had 16 offensive rebounds, converting them into 24 second-chance points, while scoring 58 points in the paint.
ShanQuan Hemphill scored 21 points and pulled down 13 rebounds to lead the Phoenix, his fifth double-double of the season.
As a team, Green Bay was held to a CIT low 37.5-percent (27-72) from the field.
Green Bay will return 78 percent of its scoring, along with four out of their five starters next season. Sandy Cohen III played his last game for the Phoenix, finishing with 13 points.