Grant Napear spent 31 years calling Sacramento Kings games. Then one tweet blew up his career.

A federal appeals court ruled Thursday that Bonneville International Corp. was within its rights to fire the longtime Kings announcer after he responded to former NBA player DeMarcus Cousins with an “All Lives Matter” message during the nationwide protests following George Floyd’s death.

Napear was off work in May 2020 and watching coverage of the protests when Cousins, a Black former Kings star then playing for the Los Angeles Lakers, asked him on Twitter, now known as X: “What’s your take on BLM?”

Napear replied that he was glad to hear from Cousins, then wrote: “ALL LIVES MATTER … EVERY SINGLE ONE!!!”

That was enough to cost him both of his broadcasting jobs.

Bonneville, which employed Napear as a KTHK radio host and the Kings’ play-by-play announcer, suspended him the next day and fired him one day later.

Napear sued, arguing that the company had punished him for personal political expression that had nothing to do with his work.

The 9th US Circuit Court of Appeals in San Francisco rejected that argument, saying Bonneville could take action to protect its public reputation.

The three-judge panel pointed to Napear’s status as a public figure and the language in his employment contract, which required him to maintain “a high standard of care and level of responsibility” on social media because it could affect the company’s “public image and reputation.”

The judges said California law does not appear to “prevent employers from limiting employees’ political expression undertaken within the scope of their employment such that it impacts the public reputation” of the employer.

They also concluded that Napear’s Twitter activity “involved his celebrity persona such that his statement fell within the scope of his professional capacity.”

Napear’s attorney, Matthew Ruggles, fiercely disputed that conclusion.

“Grant Napear actually owned that Twitter account, had published approximately 38,500 tweets before he tweeted ‘All Lives Matter…Every Single One,’ and that tweet was not made on-air, during work, or as part of any radio show,” Ruggles told The San Francisco Chronicle. “It was Grant’s personal expression, and that issue should be decided by a jury, not the court.”

Ruggles said he will seek a rehearing before the full appeals court and, if that fails, ask the Supreme Court to review the case.

The ruling upheld US District Judge Dale Drozd’s decision to dismiss Napear’s lawsuit without a trial.

The appeals panel consisted of Judges Bridget Bade, Danielle Forrest and Lawrence VanDyke, all appointed by President Donald Trump.

Drozd was appointed by former President Barack Obama.

Napear spent the next five years podcasting before returning to radio last August as a daily host on Fox Sports Radio in Sacramento.

He had also faced controversy for defending disgraced former LA Clippers owner Donald Sterling and later calling former broadcast partner Doug Christie a “coward” for not defending him after his 2020 firing.

Napear isn’t the first sports broadcaster to lose a job over social media.

Former major league pitcher Mike Bacsik was fired by a Dallas radio station in 2010 after a disparaging post about “Mexicans in San Antonio.”