Amazon will offer two lines of TVs: the Omni, which will start at $409.99, and a model called the 4-Series that will cost $369.99 and up. The TVs will go on sale in October and range from 43 inches to 75 inches.

Amazon is already one of the largest players in the connected-TV industry, thanks to Fire TV, which customers use to watch Netflix, play music or play video games. The company has sold more than 100 million Fire TV devices, including sticks that connect to TVs from companies like Toshiba and Pioneer that have Amazon software inside.

Connected TVs are one of the fastest-growing entertainment categories. Advertising on the devices will surpass $4 billion this year, according to EMarketer Inc. Amazon is competing with Roku, Alphabet Inc.’s Google, Samsung Electronics Co. and Apple Inc. to be the dominant player, bolstering its booming advertising business along the way.

Making its own TVs will allow Amazon to build hardware that best capitalizes on its voice-based technology, according to Daniel Rausch, the company’s vice president for entertainment devices and services. Customers can ask Amazon’s Alexa to recommend a new show, or to play something from Netflix without opening the app or trying to find the remote control.

The Seattle-based company declined to discuss its manufacturing partners for the new TVs.

“We believe TVs have an opportunity to do much more and be much smarter,” Rausch said.

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