The victory kept Hillgrove in a tie for second place in the region standings with McEachern and Harrison, one game behind North Cobb.
Trailing 7-0, the Hawks (6-1, 4-1) scored 28 unanswered points to take control of the game.
Justin Denton pulled in an 18-yard touchdown pass from Ironside to tie the game.
After LeMarkus Bailey recovered a fumble on the Kennesaw Mountain 35, Ironside hit Zach Katz for a 4-yard touchdown.
Quincy Nelson’s interception, set up a 48-yard touchdown run by Ironside to make it a 21-7. And Hillgrove completed the scoring splurge when Ironside connected with Omar Black on a 14-yard touchdown pass for a 28-7 lead at the half.
“I thought our kids played fine,” Hillgrove coach Phil Ironside said. “I thought our defense played well and we did what we needed to do.”
Kennesaw Mountain trimmed its deficit to 28-10 in the third quarter when Tyler Peterson kicked a 37-yard field goal, but it didn’t take long for the Hawks to answer.
On the following play, Sonny Harris raced 63 yards for a touchdown and the Hawks pushed the lead to 35-10.
“I was real proud of Sonny Harris,” Coach Ironside said. “I thought he came in and ran the ball well and filled in admirably for Richardre (Bagley), who we held out because he’s a little banged up.”
Harris finished with 148 yards on 13 carries.
The Mustangs’ got the ball back on an interception by Lucas Carmean, and it led to a Nigel Hayes 3-yard touchdown. Hayes two-point conversion run pulled Kennesaw Mountain within 35-18 contest late in the third period, but it would get no closer.
“I thought our defense did a great job of creating turnovers,” Kennesaw Mountain coach Andy Scott said about the four takeaways his team forced. “We just didn’t do a very good job offensively of maintaining the ball.”
The Mustangs also gave the ball away four times.
The Hawks pulled away with touchdowns on their final two possessions. Ironside tossed an 8-yard pass to Denton, which was followed by Matt Wilson’s 21-yard run.
Ironside completed 21-of-38 passes for 245 yards and rushed seven times for 71 yards. Denton had seven receptions for 68 yards.