The 25-year-old Portuguese striker has signed for an initial £25m deal on a four-year contract.
Beto is Everton's fifth summer signing, joining Ashley Young, Jack Harrison, Youssef Chermiti and Arnaut Danjuma in moving to Goodison Park.
Beto scored 21 Serie A goals in 61 appearances for Udinese in the last two seasons, having joined from Portimonense in the summer of 2021.
Everton are currently bottom of the Premier League table, without a point or goal from their three games so far.
Beto told evertontv: "It feels good to join Everton. I have always appreciated them as a club.
"Everton is a big, big club in the Premier League, well respected and has big history. It was easy to make this move.
"When a club like Everton tries to buy you in January and then comes again in the summer, you feel like, 'Okay, 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."
Everton manager Sean Dyche added: "We have been eager to strengthen our striking options to add more attacking quality to our squad and the arrival of Beto gives us that.
"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."
