What’s booming in wartime Odesa? Laughter.

Odesa stand-up comic Bogdan Bogachenko has the crowd in stitches as he imagines aloud the horrors Russian invaders would face if they ever tried to subdue this famously free-spirited port city.

Everyone crowded into the open-air “Hidden Garden” events venue on a recent evening knows that Vladimir Putin covets Odesa, a crown jewel of Russia’s imperial past. They know as well that Russian troops hold positions in occupied Ukrainian territory barely 100 miles away, and that the Russian navy has gamed an invasion of Odesa by sea.

So when Mr. Bogachenko takes the stage of a benefit stand-up comedy festival looking like an everyman in white T-shirt and jeans, the crowd of about 150 Odesans is ready for some fun relief.

As he launches his routine describing for the already familiar the unruly urbanization and questionable political environment the hapless Russian forces would encounter, he looks out over the crowd, pausing for effect, and says, “I really pity them.”

The audience instantly relates and roars in approval.

It’s the kind of comfort by comedy that has long been a hallmark of Odesan life – to the point where “Odesa humor” became a piece of the city’s identity, like jazz to New Orleans or gruff street talk to New York.

The city’s traditional comedy is rooted in a past of mixed cultures (the modern city of Odesa was founded by Catherine the Great in 1794 following its capture from the Ottomans) influenced by Jewish humor and was further molded by the Soviet era. But a new wave of comedy comforting Odesans these days is in no small measure the product of Russia’s 6-month-old invasion of Ukraine.

“We are experiencing a huge boom in Ukrainian stand-up comedy just in the last six months, so it’s a boom that corresponds to the beginning of the war,” says Yulia Onyshchenko, an Odesa comedian and events organizer who helped raise the funding to make the stand-up festival possible.

In a way, she says, the war has taken the vaunted Odesa humor that had become a little stale and given it new life.

“Humor really helps people pull together in times of high stress, and the stress of the war is something all Ukrainians are experiencing,” says Ms. Onyshchenko, who spent recent months organizing Ukrainian comedy shows in Berlin to raise money for her country’s war effort.

“When the comic is talking about his problems from the war in a funny way, everybody can relate to it because of this common experience,” she says. “The war has caused many Ukrainians to rediscover the importance of humor,” she adds, “but it has also given stand-up comics a new purpose.”

For Kyrilo Osadchyi, the updated style of humor he’s witnessing is helping Odesans not just to cope with the war, but also to envision a better and more united future for Ukraine.

The comedy festival’s manager and a stand-up comedian himself, Mr. Osadchyi says he appreciates how Odesa’s history as a port city and melting pot of disparate working-class cultures gave rise to a distinctive sense of humor. But he says that even before the war, the traditional comic figures of Odesa humor were losing their relevance.

“We have this rich history that gave rise to a particular style of humor, but now we want to move comedy in new directions and away from the Odesa stereotype,” he says.

As he speaks, a succession of stand-up comedians provides a backdrop of relatable tales about social media dating during wartime or common-enemy-number-one Mr. Putin. But then the boyish and somewhat nerdy Mr. Osadchyi gets serious with an evolve-or-die perspective on Odesa humor.

“As comedians we want to relate to the audience as humans to humans with common problems and common hopes for the future,” he says. “But it won’t work to do that through the old Odesa stereotypes of the funny old Jewish woman, the petty criminal, or the drunken sailor.”

Humor and the comedians who deliver it have a critical role to play, Mr. Osadchyi says. First, by helping Ukrainians cope with the hard times of war, and then by contributing to the effort he says is visible across the country: to build a new sense of unity and solidarity.

Dedicating the proceeds of the festival’s ticket sales to displaced Ukrainian kids’ education and online learning is a practical example of what he means.

But as for the actual comedy, he says, “it has to be in ways people identify with today.”

Across town at the landmark Maski Theater, theater founder and nationally recognized funnyman Borys Barskii cracks a slow, wry smile when asked about Odesa’s new generation of stand-up comics who speak of chafing at old norms and creating new means of making humor relevant.

“When we were beginning and growing into our sense of humor we said the same things, and that’s a good thing; it’s a healthy reaction for the young comics,” says Mr. Barskii, who started Maski Theater with a team of comedians under Soviet rule in 1984. With trial and practice, he adds, “they will learn to do the right thing for their times.”

But then from among all the ceramic clowns, circus posters, funny hats, and certificates of recognition that adorn his office he picks up a foot-high metal statue of Charlie Chaplin.

“‘The Great Dictator’ is the consummate example of reducing the oppressor with humor,” he says, referring to Chaplin’s classic 1940 film. Comedians will try new and contemporary ways of delivering the same point, he adds, “but there are things that are unchanging and universal.”

What that tells Mr. Barskii is that “humor itself is not something temporary, it is something very human, but it is also its own thing and it lives on,” he says.

And that just might be where a Chaplin and Odesa’s young comedians meet.

“The notion that we keep joking and helping people laugh in the dark times,” he says, “is an invincible and undying notion.”

Indeed, that desire to laugh in dark times is what brought Andrii Antonov and his girlfriend to the comedy festival. A tactical medic on three-days’ leave from the front lines in eastern Ukraine, Mr. Antonov says what appealed to him was the idea of joining with other Ukrainians in finding humor in challenging times.

“I needed some fun to put the stress away,” he says, “but here it’s better because we can laugh together.”

This desire to share laughs and create a sense of community, especially in “dark times,” seems alive and well at the comedy festival.  One comic, playing on rampant disregard for air raid sirens, tells the crowd about an audience that stayed put in anticipation of his punch line after an alert had sounded. Another relates how for a time she based her acceptance or rejection of dating app invitations on whether or not the suitor could promise her a favorite mineral water that the war had made scarce.

All of this lighthearted banter is a relief for Mr. Antonov – who describes himself as not just a native Odesan, but moreover as a product of Moldavanka, the working-class neighborhood from which Odesa humor is said to have sprung.

Maybe, he says, “that’s one more reason I’m happy here, laughing.”

Oleksandr Naselenko supported reporting for this story.