Beto, 25, who scored 21 Serie A goals in two seasons with the Italian side, is the Merseysiders' fifth signing of the summer transfer window.
Sean Dyche's Everton are bottom of the English top flight after losing their opening three matches and have failed to score a single goal.
The injury-prone Dominic Calvert-Lewin was forced out of their recent 4-0 defeat at Aston Villa after sustaining a facial injury on his return to action.
Speaking about his new signing, Dyche said: "He has impressed in a top league like Serie A for the past two seasons and scored goals.
"As a powerful striker who can carry the ball, hold up play, is strong in the air and works hard for the team, he has a lot of attributes that we hope can see him prove to be a success with Everton."
Beto, who has signed a four-year contract, told Everton TV: "When a club like Everton tries to buy you in January and then comes again in the summer, you feel like, 'OK, they want me for real', so that made the decision easy for me as well.
"My idol, Samuel Eto'o, played here, too, which makes it even more special.
"I can bring courage, I can bring confidence and I think my biggest thing is effort. I will always bring enthusiasm to the team and to our games. I feel like my style is a really good fit with Everton."
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