The full system with video is designed to be used by people sitting in a Tesla car when it isn’t moving, substituting for a karaoke booth as they relax after a day of travel or take a break at the side of the road.

Tesla is facing tough competition in the karaoke-crazed country from other EV makers, several of which beat Tesla to the market with similar combinations of software and hardware for in-car karaoke.

Singing karaoke is one of China’s most popular pastimes among the songful and tone-deaf alike. Before the pandemic, solo karaoke booths were sprouting up in Chinese malls, libraries and airports, until the coronavirus put a damper on activities in public places.

About 500 million people used online karaoke services in China last year, according to research firm iiMedia Research Group.

The TeslaMic “provides you with a mobile private karaoke room, allowing you to wander the sea of music and sing to your heart’s content,” reads a description on the company’s website.

A notice on the website says customers who missed their chance to buy a TeslaMic Friday will probably have to wait until the end of February.

A video on Tesla’s official social media account shows a young couple, each holding a TeslaMic, singing a Chinese ballad called “Little Happiness” inside a car parked at a campsite.

Though a pioneer in EVs, Tesla is playing catch-up in karaoke.

Chinese EV makers such as

Warren Buffett

-backed

BYD Co.

1211 0.73%

and

Xpeng Inc.

XPEV 3.70%

have been heavily advertising their karaoke setups, including software to simulate the experience of singing in a karaoke bar and devices such as microphones and headphones.

“I was quite jealous that BYD owners get to sing karaoke in their cars,” said Jiang Xin, 49, who owns a Tesla Model Y.

Mr. Jiang’s friend, Kevin Xu, 42, owns a BYD and enjoys singing inside the car with the doors closed and the windows rolled up. “It’s quite a way to alleviate boredom during a trip,” said Mr. Xu. “And you’re not going to be heard at all.”

This isn’t the first time Tesla tried karaoke. It included a feature called Caraoke in software for global users a few years ago that plays songs and displays song lyrics on the control panel. However, that offering didn’t include karaoke-style videos or Tesla-branded hardware such as microphones.

Tesla’s promotional video shows that its software comes from a Beijing-based karaoke service supplier, Thunderstone Technology Ltd., which supplies music videos. Thunderstone’s system is already found in several other homegrown EV brands in China.

“The space inside of a car provides users with great privacy, making it an ideal place for karaoke,” said a Thunderstone spokeswoman. Tesla didn’t reply to a request for comment.

Tesla operates an EV plant in Shanghai and sold more than 470,000 cars made at the factory last year, according to the China Passenger Car Association, roughly half its global total.

This month the company drew criticism after opening a showroom in the Xinjiang region where the government’s treatment of mostly Muslim minorities has drawn international condemnation.

Write to Yang Jie at jie.yang@wsj.com