Andy Rubin, one the creators of Google's Android software, has launched his own high-end smartphone, BBC reports.
Mr Rubin left Google in 2014 to create Playground, a technology investment company. Essential is one of the companies it funds - and the Essential Phone is its first product.
The device runs the Android operating system and has gone on sale in the US for $699 (£540).
However, it will be difficult to break into the huge market dominance of established brands.
Samsung currently has the largest share of the smartphone market, with 21% of global sales, according to analyst firm Gartner. Apple enjoys 14%.
Aside from Chinese giants offering subsidised devices, smaller firms have found it difficult to command even single-digit market share - and the Essential Phone's pricing will set it an even greater challenge.