The new phone, which comes with Windows Phone 8.1 pre-installed, is available exclusively through US network provider Verizon.
When bought with a 24 month contract, it is priced at $99 (£60), approximately 50% cheaper than the Android One M8.
"Consumers love the HTC One M8 and today's introduction extends that enthusiasm to new audiences hungry for choice in their mobile experience," said Jason Mackenzie, president of HTC Americas.
He added: "Microsoft shares our vision, and that's why we committed to bringing the Windows Phone platform to the HTC One M8."
The Taiwanese firm, which originally made its name selling early versions of Windows phone handsets, has preferred Android devices in recent years.
However it has recently lost out to rivals such as Samsung, and while its flagship handset, the HTC One, received good reviews, these did not translate into strong sales.
In April, HTC posted losses of 1.88bn Taiwanese dollars (£37m; $63m) for the first three months of 2014, compared with a profit of T$85m a year earlier.
Shares in HTC have dropped by 38% in the past year.