The 225-room Atlantic Tower Hotel and the 220-room Haydock Park Hotel in Merseyside will undergo major refurbishments and bring the total number of Amaris properties trading under Accor to 32.
The move forms part of a wider investment plan to boost the value of Amaris's 89-strong portfolio from £1.5bn to £2bn over the next three to five years.
The company - which was created by American private equity group Lone Star in July - is spending £100m on re-branding 21 hotels to Mecure and Jury’s Inn sites and £30m converting three of its properties to the Hilton brand.
Steven Devine, general manager of The Atlantic Tower, said: “This is fantastic news not just for the hotel, but also for the city as another world renowned brand is bringing investment into Liverpool.
"Money will be spent on refurbishing parts of our property, in particular some of our rooms and suites, and also on other elements such as uniforms for our 110 strong team."
Amaris CEO John Brennan described the investment as a key part of the group's strategy to create 'the UK’s best performing, most exciting hospitality investment and management company'.