One day in late March, John Mayer went online and posted a preview of some new music. The eight-bar fragment, which spotlighted a buoyant electric-guitar-and-keyboard figure laid over a clean and unfussy backbeat, was suitably Mayer-esque. The forum in which he chose to reveal it—TikTok—was not.

How did he wind up there? “I don’t ever want to be the type of artist or person who goes, ‘no, no, no,’ ” Mr. Mayer says simply. But there was another consideration: “Once you get past the age of 40, anything can be Elvis. And you have to be very careful that you’re not the guy shaking his head at Elvis.”

Mr. Mayer is 43, placing him well outside the target age range of the quick-cut, dance-challenge-heavy, youth-dominated social media juggernaut. But, he says, the head of his record label urged him to join the platform, and so he made quick work of its potential as a vehicle for both interactive engagement and passive absurdist humor. He invited users to join him in virtual jam sessions and instructed them on how to play his songs. And he posted clips that showed him peeling a Sumo orange and ruminating deeply on “even numbers that seem odd to me” (for those wondering, 13,712 is among these).

Over two months, he’s accumulated more than a million followers. The new music that he teased on TikTok back in March will now be out as a single, “Last Train Home,” on June 4. It will be followed, on July 16, by the companion album, “Sob Rock,” his first in four years and eighth overall.

Mr. Mayer has long exhibited a talent for navigating assorted musical genres, age demographics and media pursuits. He has worked onstage as a stand-up comedian and on network TV as a late-night talk-show host. He stars in his own low-budget Instagram Live interview series, “Current Mood.” And he was a relatively early adopter of the exclusive audio-only app Clubhouse, where he has dropped in unannounced to hold court on a variety of topics for thousands of listeners. Mr. Mayer is getting ready to tour U.S. stadiums and sheds this summer and fall, with the Grateful Dead offshoot Dead & Company.

If not for the Covid-19 lockdown, Mr. Mayer says, he may not have made a record at all. “At the very least, not this one.” This past pandemic year has been, on a grand scale, a “frightening, unbelievably tragic thing,” he says. Where it led him musically was to a place of reassurance. “Sob Rock” is a record “made to bring comfort.”

There’s a distinct 1980s soft-rock vibe lurking within its melodies and grooves. “I asked myself, ‘What music makes me feel like everything’s going to be OK?’ ” Mr. Mayer says. “And it’s the music I listened to growing up in the ‘80s. There’s a security-blanket aspect about that sound that reminds me of a safer time.”

“Last Train Home,” like many songs on “Sob Rock,” juxtaposes lush chording and breezy cadences with serious subject matter, in this case, a relationship in distress (“If you wanna use me, then you gotta use me ’til I’m gone,” Mr. Mayer sings in the first verse).

“The songwriting on the record is decidedly modern—there’s no throwback sensibility,” says Don Was, a producer who has worked with Bonnie Raitt, the Rolling Stones and Bob Dylan, and who has helmed two Mayer albums in addition to “Sob Rock.” “As a musician and a songwriter, he’s as good as anybody at finding something that’s going on in his emotional inner life and expressing it eloquently.”

Aside from a solo career that’s led to multiple Platinum-certified albums and singles, seven Grammys and his own PRS signature guitar model, Mr. Mayer is a first-call collaborator when newer artists ranging from Leon Bridges to Khalid to Maren Morris (to name just three recent examples) are looking to add a certain something—usually a subtly bluesy and highly melodic guitar accompaniment—to a track. With Dead & Company, he’s a pivotal member, but also the youngest participant by some years.

“John is a musician’s musician,” says original Grateful Dead guitarist and vocalist Bob Weir, who is also Mr. Mayer’s band mate in Dead & Company. “That’s where his sensibilities lead him and that’s what you get from him.”

Even as Mr. Mayer speaks of finding “joyous” shelter in the music of his childhood on “Sob Rock,” his conversation is preoccupied with notions of maturing and, as he puts it repeatedly, “aging gracefully.”

He has made a clean break from the serial-dating, controversial-interview-giving tabloid version of himself that provided fodder for the media machine in the early 2010s, remarking, “I do think that at a certain point you are allowed to take all your loose ends, put them in a box and lock them up and say, ‘We never have to talk about that again.’ ”

And going forward? “I’m not a make-the-same-mistake-twice kind of guy.”

Mr. Mayer has also taken a breather from TikTok (for now), conceding that pulling back “is a new feeling for me as a former ‘gotta be there’ guy.”

“As I get older, there is this slowing down of the need to sort of run every play in the book,” he says.

This would seem at odds with his decidedly full plate: his own new solo album, a Dead & Company tour (“it’s a lot of work to memorize 120 Grateful Dead songs,” he points out, “but it’s this place where I can turn around, look at my own music and say, ‘I’m going to leave you here for a second and go do this’ ”), and, as he puts it, “all these other projects that are coming down the pike.”

Busy schedule to the contrary, he says, “it’s quieter in my head than you might think. I don’t apply too much context to things other than, if it feels good and it feels honest and I won’t regret it—and I’m pretty good at sensing those things now—then I’ll do it.”