Johnson carded an eagle, five birdies and a solitary bogey to set a testing clubhouse target as a strengthening wind made conditions difficult for the later starters.
At six under par, Johnson held a two-shot lead over a seven-strong group which included playing partner Jason Day, with English pair Justin Rose and James Morrison another shot back on three under.
The last time the US PGA was held at Whistling Straits in 2010, Johnson was one shot ahead with one to play and thought his bogey on the 18th meant he would be heading into a play-off with Martin Kaymer and Bubba Watson.
However, the 31-year-old was then penalised two strokes after it was ruled he had grounded his club in a fairway bunker before hitting his second shot, even though spectators had been trampling all over the hazard.
Johnson had also squandered a three-shot lead in the final round of the US Open two months earlier and he three-putted the 72nd hole at Chambers Bay this year to finish a shot behind Jordan Spieth.
The world No 8, who led after the first and second rounds of the Open before fading badly at St Andrews, started on the back nine and made birdies on the 10th and 11th before holing from 30 feet for an eagle on the 16th.
Further birdies on the first and second were followed by a bogey on the third, where playing partner Rickie Fowler needed four shots to escape a bunker and took seven, but Johnson bounced straight back with a birdie on the fourth.
“Today was pretty easy, I would have to say,” Johnson said. “I was swinging well and I was hitting the shots where I was looking and I really felt like I was just super patient, stayed focused all day.
“I played pretty well at the US Open on the weekend. At the British Open I didn’t play well on the weekend, but even the first two days I didn’t feel like I was playing that good golf. I wasn’t too comfortable with my swing. I wasn’t hitting the shots that I wanted to hit. I didn’t feel like I was too much in control.
“Today, I really felt like I had my ball under control a lot like I did at the US Open. We’ll just have to see what happens. It’s only the first round, we’ve still got a lot of golf to play.”
While Johnson was relishing his opening round, it was a familiar story from the former world No 1, Tiger Woods, who blamed his putting after struggling to an opening round of 75 .
Woods, who missed consecutive cuts in major championships for the first time in his career in the US Open and Open Championship, faces a battle to avoid another early exit after carding five bogeys and two birdies.
“I hit it great today, but I made actually nothing,” Woods said. “Probably one of the worst putting rounds I’ve had in a very long time. But I hit it good today, so that’s about it.
“I just had no feel at all for the speed [on the greens]. It was awful.
“My speed was bad, hence speed determines line, so that was off. I either left them short or blew them by. Just didn’t have the speed at all.”