Broadhurst teed off in the early wave of players, collected seven birdies and an eagle to go with just one bogey, and watched as his lead held up for the remainder of the day.
Swede Christian Nilsson bogeyed his last hole and finished the round at 7-under-par 65 to stand alone in second place. Christian Cevaer of France is one stroke further back in third place after an opening-round 66.
Richard Finch of England, Swede Jarmo Sandelin and Carl Suneson of Spain are tied for fourth place at minus-4.
Broadhurst's score equaled the Le Meridien Penina course record established by Robert Karlsson and Terry Price.
'It's nice to go low. I haven't been that low for years,' said Broadhurst, who needed just 24 putts in the round. 'I have had a couple of 66s and 67s, but I haven't shot under 65 for quite a few years.'
Broadhurst began his round on the back nine with consecutive birdies to burst into red numbers. He stumbled to a bogey at the par-3 13th after knocking a 4-iron in the water, but that would be his only dropped shot of the round.
The 40-year-old regained that stroke, plus another, with birdies at 14 and 18 to make the turn at 3 under.
Broadhurst made a real move on the front nine, where birdies at the third, sixth and seventh served as icing on the cake to his eagle at the 493-yard, par-5 fifth.
He was at minus-8 heading to the final two holes -- a par-3 and par-4 -- but could only manage pars to close out the round.
'In the back of my mind, when I was playing the eighth I was thinking of 62, which was my lowest round ever,' said Broadhurst. 'But it was not to be.'
Broadhurst's victory here last year was his first European Tour title in a decade. Barry Lane and Paul Lawrie shared the lead heading to the 17th, but faltered down the stretch.
'I'm not pulling any wool over my eyes -- I know that the irons are not how I would like, feeling-wise -- but that's just a case of perseverance really until you get it right,' Broadhurst commented on his round Thursday. 'But I am pleased with today because there were no real signs of being able to hit 64 beforehand.'
Lawrie opened with a 4-under 68 and shares seventh place with three other players. Joining him at minus-4 were Nicolas Colsaerts, Rafael Gomez and Stuart Little.
There are 23 players within five shot of Broadhurst's lead, and 80 players even-par or better.
Meanwhile, 'Big Break IV''s Paul Holtby made his European Tour debut, shooting 4-over 76.