Langer won the title at Carnoustie in 2010 but lost in a playoff at Royal Birkdale last year. He also led going into the final round at Turnberry in 2012, only to fade on the final day.
That seems unlikely to happen again on Sunday given the German's three-day master class on the sun-kissed South Wales links with earlier rounds of 65 and 66.
Langer had to settle for his third round's fourth birdie on the 18th after missing an eagle chance from 10 feet. He dropped his only shot on the par-4 10th.
''I played very nicely, got off to a good start ... Then I maybe played a little safe for a couple of holes,'' Langer said. ''I can't believe how far I hit it on the last.''
Canadian Rick Gibson was Langer's nearest challenger at 6-under 207 after a 66, hitting back with six birdies after dropping a shot at the first. Bob Tway of the United States was third, a further stroke back after a 68.
Americans Tom Watson and Scott Dunlap shared fourth place on 209 with England's Chris Williams, while Scotland's Colin Montgomerie, England's Barry Lane and Fred Couples of the United States were tied for seventh on 210.
Montgomerie, bidding for his third successive senior major, matched Langer's 32 over the front nine but then slipped to a 4-over 40 coming home.
''Bernhard's the best player out here and he's proving it,'' said Montgomerie. ''I had a horrendous back nine, now the best I can do is second.''
Tenth-placed Jeff Sluman had a superb opening to his third round with four straight birdie threes, before dropping a stroke at the short No. 5. He then eagled the long sixth and birdied the seventh. He finished with two pars to be out in a week's best 6-under 29 but the American couldn't sustain it, dropping three shots and picking up just one birdie to be back in 38 for a round of 67.
Playing partner Dunlap was five strokes worse than Sluman on the way out, but then came back in 31 with three birdies and an eagle, for a 65.
Between them, they had a 13-under better-ball score of 58.
Philip Walton equaled the record low round of the week of 64 to move from 7 over to level par 213.
The Irishman had four birdies and dropped just one shot on the way out, then had five birdies and one bogey on the way home for two nines of 32.
New Zealand's Greg Turner recorded the first ace of the week when he holed his 9- iron tee shot at the 165-yard 15th on his way to a 66.