Sparked by Gerald Smith's 79--yard touchdown run, Howard rallied in the second half to defeat River Hill, 17-7, and earn its first county title since 1993.
The No. 7-ranked Lions (9-1 overall, 8-1 league) are county co-champs with Wilde Lake.
Howard also won the Class 2A South Region championship and earned its first playoff berth since 1993.
"It's awesome," said Lions line-backer Joey Tortella, who made 12 tackles and had 10 assists. "I never thought it'd happen - region and county champs. The team just came together and everyone had an impact in this game."
The victory at River Hill also vindicated Howard coach Vince Parnell, who was fired as Lions head coach in 1985 and rehired in 1995. "This isn't bad for someone they said couldn't coach," Parnell said.
River Hill (7-3, 6-3), a county title and playoff contender before being upset by Mount Hebron a week ago, was led by Dyami Jenkins (20 rushes for 167 yards) and Jason Fawcett (23 for 100).
River Hill coach Don Van Deusen said: "Penalties hurt us and the missed field goal. Howard used its team speed and their offensive line blocked well. I'm happy for Vince (Parnell)."
Smith, a senior who has orally committed to Penn State, led Howard with 176 yards rushing on 15 carries despite a bruised left knee that he injured early in the game. He had iced his knee and stretched the leg at least a half-dozen times on the sideline during the game.
"It didn't hurt when I ran but hurt a lot when I stopped running," Smith said. "My coach was getting on me for running soft and I had to prove I wasn't. It was my turn to step up. This team plays us tough every year."
Howard drove 67 yards on 10 plays on its first possession and settled for a 30-yard field goal by Marc Benson to lead 3-0.
An offside penalty on third-and-goal at the 5 eventually forced River Hill into a failed field-goal attempt, which followed a 62-yard drive after Howard's score.
Howard fumbled a punt and Mark Tossie recovered for River Hill at Howard's 38 to give the Hawks another scoring chance. But they came up inches short on fourth down at the 18.
Howard fumbled again on second down, as Jake Adams delivered a big hit and Mike Hatcher made the recovery for River Hill at the 15.
This time River Hill scored on a 6-yard pass from quarterback Matt Hostetler to Adams. Howard's Antuan Jones tried for an interception but just missed on the Scoring play.
River Hill drove 45 yards in the third quarter to Howard's 15, but on fourth-and-one drew an illegal motion penalty that killed the drive.
That opened the door for Smith's weak-side sweep for 79 yards that put Howard ahead, 10-7. It was his longest run this season.
"They tried to contain outside and I just cut back inside and gave it all I had," Smith said.
With 9:50 left to play, Jones scored on a 14-yard pass from Boomer Durham, capping a 75-yard drive that was highlighted by Smith's 33-yard run. River Hill drove as far as Howard's 11 late In the game, but an offensive pass interference penalty ended that drive.