Captain Gilly Flaherty is among five West Ham players to sign new contracts with the Women's Super League club.
The 28-year-old defender, forwards Alisha Lehmann, 21, and Adriana Leon, 27, will remain with the Hammers until 2022, as well as South Korean midfielder Cho So-hyun, 32.
France midfielder Kenya Dali, 28, has agreed a new one-year deal.
Hammers boss Matt Beard said the quintet "have proven themselves to be key individuals".
West Ham, who finished eighth in the table after the 2019-20 season was curtailed and decided on a point-per-game basis, are set to return for pre-season training in the coming week.