According to Johnson, Mysterio had hoped to sign for only 18 months but eventually settled for the two-year deal on offer from WWE. It's unclear when he'll make his full-time return to the company, though.
Wednesday's news has felt inevitable after he showed up in the 2018 Royal Rumble match in January. He then came back for the 50-man Greatest Royal Rumble match in April.
WWE furthered the speculation in June when it announced Mysterio was a pre-order bonus for the WWE 2K19 video game. In the past, the company has used the video game to tease the WWE debut of Sting and return of legends such as Kurt Angle and Bill Goldberg.
Shortly before the 2K19 news, Mysterio acknowledged during an interview on Mighty 1090's Scott and BR in San Diego that he and WWE were "going back and forth" on a contract and that it was "looking really good for a possible return."
The question now is when WWE plans on getting Mysterio back on its programming.
The Super Show-Down in Melbourne, Australia, is Oct. 6, so it might be too late to feature him on that card. Crown Jewel on Nov. 2 is the next major show on which Mysterio could wrestle. Since WWE is likely to once again send as many possible stars to Saudi Arabia for its second event there, that might be the most likely option.