Henry looked set to cruise home heading into the closing holes, but while he finished bogey-par-par, nearest challenger Rocha completed his final round par-birdie-birdie.
However, that was not quite enough to deny Henry, who finished one point clear of Rocha on 43 points under the modified Stableford scoring system.
Henry's final round was easily his worst of the event, following up scores of 10, 12 and 14 in the first three days with a return of seven points today - from four birdies and one bogey - but it was still enough to end the 37-year-old American's six-year wait to earn another PGA Tour title.
Brazilian Rocha, who led after the second round, was runner-up with nine points in his final round, while first-day leader Andres Romero of Argentina was third on 37 points after scoring just the six points today.
John Mallinder, who started the day in third four points behind his countryman Henry, had to settle for fourth place after only picking up two points with a round that included two birdies and two bogeys.
England's Gary Christian had a final day to forget as his chances of a first PGA Tour victory of the season disappeared in a nightmare front nine.
The man from Carshalton began the day in the top 10 but double-bogeys at the fourth and seventh holes, combined with bogeys at the first, third and nine, saw him tumble down the leaderboard.
The 40-year-old eventually ended up with minus-five points for his round to finish the tournament in joint 21st place on 23 points.
Ireland's three-time major winner Padraig Harrington was joint 19th on 24 points after completing his event with just a one-point haul today, with his round including three birdies, two bogeys and a double-bogey.