Simon Khan, Francesco Molinari, Marcus Fraser and Shiv Kapur shot 67, and Ernie Els was among a group of five with 68s.
Rose was playing in his first event since being sidelined with a back injury following his fifth place at the Masters in April.
"I putted well today. It's funny because I haven't done much putting since I started practicing again," said Rose, who made his name by finishing fourth at the British Open in 1998 as a 17-year-old amateur. "The putter has felt great in my hands."
The 28th-ranked Rose made five birdies against two bogeys on the front nine, then added birdies at the 11th, 15th and 16th holes.
Broadhurst, a 1991 Ryder Cup player who narrowly missed making the team last year, missed the cut by three shots at last week's Irish Open.
"I was searching for answers," Broadhurst said. "Today I got rid of technique and just tried to hit the ball down the golf course."
Broadhurst birdied four of the first six holes, including a 25-yard chip-in at the fourth. He made his only bogey at the ninth after driving into a bunker, but then birdied the 11th and 17th.
"I've had some horrors around here over the years," Broadhurst said. "I always seem to come in struggling with my game."
Els, playing on a course he had a large role in redesigning, had five birdies on the back nine.
Vijay Singh and Paul Casey shot 73, Casey having to overcome a quadruple-bogey nine at the 12th.
"That could have ruined my championship," said Casey, happy to have made three birdies after the nine. He won the World Match Play title on the same course last fall.
Els struggled on the front nine, three-putting the seventh and ninth holes. He birdied 11 and 12, then three in a row from the 15th.
Els said he received mostly positive feedback from players about the course changes he has made over the last year, including some new bunkers.
"I almost feel I'm hosting the golf tournament," Els said.