In January 2018, Reynolds started the production company Maximum Effort and signed a three-year first-look deal with Fox, starting development on a live-action adaptation of the board game Clue, to be penned by Deadpool writers Rhett Reese and Paul Wernick. Additionally, in April 2019, Reynolds shot Free Guy, an action comedy directed by Shawn Levy in which Reynolds will star as "a background character who realizes he's living in a video game. With the help of an avatar, he tries to prevent the makers of the game from shutting down his world". In January 2019, it was announced that he would return as the voice of Guy in the sequel to The Croods.
In 2018, it was announced that Reynolds was cast in the Netflix action thriller film 6 Underground, directed by Michael Bay. The film was released on December 13, 2019.
On May 13, 2018 broadcast of the South Korean reality television show King of Mask Singer, Reynolds had a special performance in the opening act, singing "Tomorrow".
Reynolds acquired a stake in Aviation American Gin in February 2018. He stated that his interest went beyond that of an owner, and that he planned to oversee the product's creative direction as well as taking an active role in the business. In November 2019, he purchased an ownership stake in Mint Mobile. In July 2020, he joined the board of Match Group. On September 23rd 2020, it was announced by the Wrexham Supporters Trust that a business partnership consisting of Reynolds and fellow actor Rob McElhenney were in talks to purchase Wrexham AFC.
Reynolds has openly spoken about his lifelong struggle with anxiety, noting in 2018 that he carried out many interviews in the character of Deadpool to alleviate his fears. He became an American citizen circa 2018.