Meg Whitman, the former chief executive of eBay Inc. EBAY, -1.20% and Hewlett Packard Enterprise Co. HPE, +0.00% , is jumping into esports, the burgeoning business of professional videogame playing.

Whitman has invested in Los Angeles-based Immortals LLC, a global esports company founded in 2015, and will join its board, she said in an interview Monday. Immortals owns and operates an esports franchise, the Los Angeles Valiant, in a league run by videogame publisher Activision Blizzard Inc. ATVI, +0.13% that was launched in January.

It isn’t clear how much she put in but Whitman’s investment values the company at more than $100 million, a person familiar with the matter said.

The global audience for esports has ballooned to 400 million viewers, according to Whitman. The industry’s annual revenue — from corporate sponsorships, media rights, ticket sales and other sources — has more than doubled since 2014 to more than $800 million and is expected to continue at a fast clip, she said in the interview.

An expanded version of this report appears on WSJ.com.

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