Comcast Corp. unveiled a smart TV for the U.S. market, as the cable giant looks to become a dominant distributor of streaming apps and give a boost to its homegrown Peacock service.

The new XClass TV will be sold primarily through Walmart Inc., beginning with availability in select stores this week. The first model is being manufactured by China’s Hisense, with the lowest cost option priced at under $300.

The...

Comcast Corp. unveiled a smart TV for the U.S. market, as the cable giant looks to become a dominant distributor of streaming apps and give a boost to its homegrown Peacock service.

The new XClass TV will be sold primarily through Walmart Inc., beginning with availability in select stores this week. The first model is being manufactured by China’s Hisense, with the lowest cost option priced at under $300.

The Wall Street Journal earlier reported Comcast was developing plans to distribute smart TVs in partnership with Walmart and manufacturers including Hisense. The company plans to expand its distribution and manufacturing partners in the future.

With its push into smart TVs, Comcast is taking on players such as Roku Inc. and Amazon.com Inc. as a hub for consumers to access streaming services. That transition is becoming more urgent as more consumers cut the traditional TV cord and turn to streaming for entertainment, sports and news.

Many companies, including Comcast, already offer streaming set-top boxes like Apple TV or Amazon’s Fire TV. But building streaming software directly into TV sets has advantages, including lower costs that translate into higher profit margins, industry executives say. Roku-powered TV sets are already on the market.

Comcast will be selling its sets nationwide. The Philadelphia-based company has been finding ways to move outside its regional footprint.

The new XClass set gives Comcast a chance to promote its own streaming service, NBCUniversal’s Peacock app. Those who buy the TV will receive a 12-month free subscription to Peacock’s premium tier, which costs $5 a month and includes advertisements. Comcast customers already receive a Peacock subscription free if they have a cable subscription or one of the company’s Flex streaming boxes.

Those who buy the XClass TV will get a 12-month free subscription to NBCUniversal’s Peacock premium tier.

Photo: Tiffany Hagler-Geard/Bloomberg News

Peacock now has 54 million sign-ups and more than 20 million monthly active accounts, the company said in July. Comcast hasn’t disclosed how many users pay for the service.

Earlier this month, Comcast entered the smart-TV market outside the U.S. with Sky Glass, which will be available to customers of Sky, Comcast’s European pay-TV unit.

Both XClass and Sky Glass are built on the sophisticated software that Comcast has built in recent years to power its advanced cable and streaming set-top boxes.

Like its peers in the pay-TV industry, Comcast has been losing cable customers as consumers flee the traditional bundle for streaming services. The company had nearly 19 million cable-TV customers as of June 30, after losing 399,000 during the second quarter. The company reports third-quarter earnings next week.

Write to Lillian Rizzo at Lillian.Rizzo@wsj.com