The 9-year-old gelding owned by George Strawbridge, Jr. and trained by Jonathan Sheppard was making his fifth start in the Sycamore. He won the race in 2001 and 2002.
"I'm very happy for the horse," said Sheppard. "He's been knocking on the door but not crossing the wire first. We kind of needed this today. He takes good care of himself and we try to take good care of him."
Still sixth at the top of the stretch, the son of Green Dancer gradually advanced on the outside and held a clear advantage at the finish of the 1 1/2-mile turf race timed in 2:34.30.
"I wish they were all that fun to ride," said the 42-year-old Stevens who is closing in on his 5,000th career victory. "He's nine years old and has just about as much experience here as I do.
"He was happy with his position early on and picked it up on his own. He made my job easy."
Dreadnaught finished second in the field of eight older horses. He was a half length in front of Vangelis, the 7-10 favorite. Clear Forecast finished fourth followed, in order, by Noble Masterpiece, Let It Thunder, Tempered Steel and Ball Four, the early leader.
Rochester paid $14.60, $6.80 and $3 as the third choice. Dreadnaught, ridden by Jean-Luc Samyn, returned $7.20 and $3.40 and Vangelis with Edgar Prado aboard paid $2.10.
Rochester improved his lifetime record to 45-11-11-4 and increased his earnings to $1,183,309.