A Loudon Love free throw with 7:37 to go restored a nine-point lead for the Raiders, who held on from there.
The Phoenix got within four on a 3-pointer by Jayquan McCloud with 5:37 to go, but Vest gathered a loose ball under the basket and banked it in while being fouled.
He converted the old-fashioned 3-point play to restore a seven-point advantage with 5:23 to go.
Bill Wampler scored on the block for Wright State to make it 59-50 when drew an offensive foul at the other end, and Green Bay never got closer than eight the rest of the way.
Wampler led all scorers with 18 points while Love had 10, Cole Gentry scored nine and Smith had nine.
Vest finished with seven.
Love also had 12 rebounds for the regular season co-champions while Sandy Cohen III led Green Bay with 13.
***FIRST HALF RECAP***
Wright State leads Green Bay 33-20 at halftime of a Horizon League tournament semifinal at Little Caesar’s Arena.
The top-seeded Raiders used an 8-0 run midway through the first half to take control of the game, a spurt that started and ended with Bill Wampler 3-pointers.
They sandwiched a Loudon Love layup and left Wright State ahead 23-15 with just under six minutes to go in the opening stanza.
After Green Bay broke the run with a Sandy Cohen III jumper, another Wampler trey made it 28-17 with two minutes to go.
The Raiders led by as many as 16 in the first half, but a PJ Pipes 3-pointer at the buzzer for the Phoenix let them go to the half trailing by only a baker’s dozen.
The Raiders are the No. 1 seed and defending champions
Wampler led all scorers with 12 points in the first half while Love scored six points and grabbed eight rebounds.
Cohen led Green Bay, the No. 4 seed, with seven points.
Neither team shot the ball well from the field, but the Raiders were 5 for 14 from the 3-point land while the Phoenix were 2 for 5.
Wright State outscored Green Bay 6-0 at the free-throw line, too.
The winner of the first semifinal will play No. 2 seed Northern Kentucky or No. 3 Oakland in the championship game at 7 p.m. Tuesday night.
The Wright State women, who like the men’s team are the No. 1 seed, are set to face No. 2 Green Bay in the Horizon League women’s tournament at noon Tuesday.
The WSU women beat IUPUI earlier Monday.