Westwood's 63 was two strokes better than John Daly's 65, which he shot at Gut Kaden Golf Club last year.
The opening round was completed despite a two-hour, 35-minute weather delay caused by thunder and lightning.
World No. 5 Retief Goosen joined Robert Karlsson in a tie for second place at minus-8. Jean-Francois Remesy, Ian Woosnam and Gregory Havret were one stroke further back at 7-under-par 65.
Westwood started on the back nine Thursday. He nearly holed his approach at the 12th, but kicked in the 18-inch birdie putt. He made it two in a row as he rolled in a 10-footer for birdie.
The Englishman started a run of four straight birdies with an 8-foot putt on the 15th. After a 20-foot birdie putt at the next, Westwood two-putted for birdie on the par-5 17th.
Westwood dropped a wedge 15 feet from the hole at the 18th to turn in minus-6. He parred the first three holes of the front nine. On the third, he managed to save par despite finding water with his second shot.
At the fourth, Westwood tapped in a 2-foot birdie putt. He two-putted for birdie on the sixth, then sank a 15-footer for birdie at seven to move to minus-9.
'I'm delighted,' exclaimed Westwood, the 1998 and 2000 champion here. 'Today it was just a case of building up my confidence all the time. From tee to green my confidence is high.
'I've got good control of the ball. There's nothing like holing putts to give yourself confidence on the greens, so it was nice to roll a few in today that I've been missing. That was a step in the right direction.'
Goosen drained back-to-back birdies from the 12th and 17th. He also eagled the par-5 15th to head to the front side at minus-6. The South African dropped a stroke on the fourth, but birdied three in a row from the fifth to move into second.
'I'm happy to get off to a good start,' Goosen said. 'You never want to go and shoot level par out here today because you know you're going to be nine or 10 shots off the lead. I got off to a nice start on my back nine this morning, four birdies and an eagle. Then I had my chances for a much lower round really, but the bogey on four sort of stopped a really low round and from there on I made three nice birdies coming in.'
Karlsson also played on the back nine first. He collected birdies on 13 and 16 before an eagle on 17 got him to minus-4. He dropped in a birdie on the second and made it two straight with a birdie on No. 3. Karlsson converted birdies on six and seventh to get to 8 under.
Angel Cabrera, Stephen Gallacher, Joakim Haeggman and Garry Houston share seventh place at 6-under-par 66. Defending champion Niclas Fasth opened with a 4-under-par 68 and is tied for 21st.