[3] It was the first major held at Harding Park, which had previously hosted World Golf Championship events in 2005 and 2015, and the 2009 Presidents Cup.

In his PGA Championship debut, and second major appearance, Collin Morikawa won by two strokes ahead of runners-up Paul Casey and Dustin Johnson.

The top three players in the world rankings heading into the tournament were Justin Thomas (winner of a WGC event the previous week), Jon Rahm, and Rory McIlroy, but none of them were able to contend for the title.

Among the former champions not to play were Yang Yong-eun, Pádraig Harrington, John Daly and Vijay Singh, who withdrew due to various concerns about the COVID-19 pandemic, health and injury.

Among the invitees was Li Haotong, one of few from outside the top 100 in the world rankings; he went on to lead the championship by two strokes at the halfway stage,[20] before finishing in a tie for seventeenth place.

[21] Among the withdrawals were leading European players Lee Westwood and Eddie Pepperell who, like Harrington, cited concerns surrounding the COVID-19 pandemic and traveling to the United States.

[22][23] The last player to qualify was Richy Werenski, who gained his place by winning the Barracuda Championship the week prior to the PGA Championship, and the final player to take their place in the field was twelfth alternate Alex Norén, who had missed out on automatic qualification as a member of the European Ryder Cup team in 2018 having dropped out of the top 100 in the world rankings.

[31] Friday, August 7, 2020 Li Haotong, the 114th-ranked player in the world, shot a bogey-free round of 65 (five under par) to take a two stroke lead after 36 holes.

Among those who missed the cut were Martin Kaymer and Zach Johnson, who were tied for third place after the opening round; Jim Furyk and Richy Werenski, who had both won tournaments the previous week; and Rickie Fowler, who whiffed a short putt on his sixteenth hole of the day and went on to finish just one stroke outside the cut-line, ending a run of 14 cuts made in major championships.

They were first round leader Jason Day, Daniel Berger, Justin Rose, Tommy Fleetwood, Tony Finau and Bryson DeChambeau.

Morikawa, making his PGA Championship debut, was the first to reach 11 under par with a chip-in for birdie from 54 feet off the front of the green at the 14th hole.

Playing in the group behind Casey, Morikawa found the green with his tee shot at the 16th and holed his putt from seven feet for eagle to open up a two stroke lead.

Brooks Koepka, attempting to become the first player since Walter Hagen to win three straight PGA Championships, began the day two shots back but was four over par for the first nine holes and dropped out of contention; he closed with a round of 74, the second-worst of anyone in the field, to tie for 29th place.