The granddaddy of all sports networks is getting into business with the granddaddy of all playground games.

ESPN has signed on to televise this year’s USA Rock Paper Scissors League championship — helping give the nascent sport an air of legitimacy.

“This is a milestone for the sport,” said USARPS League co-commissioner Matti Leshem. “It’s a real validation.”

The second annual national championship tournament, sponsored by Bud Light, will take place May 12 and 13 at the Mandalay Bay Hotel and Casino in Las Vegas. Finalists will secure a spot at the tourney by winning a local qualifying contest in 325 regional markets; the ultimate winner will take home $50,000.

Last year’s first-ever tourney ran on A&E. Leshem — who exec produced the gamer “2-Minute Drill” for ESPN — said ESPN made more sense for the league as the sport “matured.”

ESPN programming and acquisitions director Ilan Ben-Hanan said the channel felt the competish would be a “fun” alternative for its viewers. The sports cabler is no stranger to nontraditional sporting events, having televised the National Spelling Bee and several major eating competitions (including the annual Nathan’s hot dog battle).

“Nearly everyone has played Rock Paper Scissors, so it will be interesting to see the strategic skills displayed by this elite field of competitors,” Ben-Hanan said.

ESPN will air an hourlong special on the championship sometime this summer.

Last year, Dave McGill won the $50,000 grand prize after playing his hand — literally — with what organizers call “the paper heard ’round the world.”

Leshem and co-commissioner Andrew Golder have also launched online competition “The Hunt for the USARPS Hotties” to select this year’s official “RPS Girls.” The commissioners hope to turn the “Hunt” into another special.

Exec producers Leshem — who runs the production shingle Protagonist — and Golder — who’s behind the NBC reality entry “Identity” –launched the USARPS in 2005.

Leshem first got involved with Rock Paper Scissors after reading about the World RPS championship in Canada. He secured the TV rights to the event and produced a special for Fox Sports Net’s “Best Damn Sports Show” in 2004. That experience eventually led to his USARPS brainchild.

Another sign the USARPS has scored some legitimacy: McGill has scored a guest spot on an upcoming seg of Golder’s “Identity.”