Beard led Liverpool to back-to-back WSL titles in 2013 and 2014 during his first stint at the club, before returning to the side in 2021 and guiding them back to the top-flight after two seasons in the second tier.
He left Liverpool in February, with his last coaching role coming in a brief spell in charge of Burnley between June and August.
"The thoughts of everyone at the club are with Matt's family and friends at this devastating time," Liverpool said in a statement.
"Matt was not only an extremely committed and successful manager, he was also a person of real integrity and warmth, who will always be remembered with genuine fondness by everyone he worked with at the club."
Beard began his managerial career at Millwall before moving to Chelsea in 2009. He also coached West Ham United, Boston Breakers and Bristol City.