The Spanish side revealed the transfer had been finalised, with the Portugal international penning a five-year deal with his new employers:
During his time in the Primeira Liga, Carvalho emerged as one of the finest deep-lying midfield players in the division. Betis manager Quique Setien will now hope he can make an impact in La Liga next season. Here's a look at what to expect from the midfielder:
Football writer Simon Harrison offered his view on the signing:
Simon Harrison @simonhfootball
If you’d have said 12 months ago that Betis were going to have Marc Bartra and William Carvalho in their squad for 2018/19, they would have laughed. Setién has turned things around and now their style of play and how they are doing things on and off the pitch tempt big names.
There has been a lot of hype and subsequent discussion about Carvalho in recent years.
The 26-year-old clearly has a lot to offer. Carvalho, primarily, is a huge presence in the middle of the park. His large frame makes him a tough man to bypass in midfield, able to bully opponents out of possession, challenge in the air and step in to stop attacks.
On the ball, he has quality, too. Carvalho has great composure in his distribution; he's not a long, raking passer of the ball, but he is sharp in laying possession off quickly. Additionally, the Selecao man has a turn of pace that can see him scythe through the middle of the pitch, quickly converting defence into attack for his team.
WhoScored.com highlighted his dribbling ability:
They are qualities he has shown at the highest level. Carvalho has performed well for Sporting in Europe, while he's also done well for Portugal on the international scene, particularly helping the team win the 2016 UEFA European Championship.
There are improvements Carvalho will need to make with Real Betis. Occasionally, he can lose focus when he's not tasked with doing too much defending, while his tackling can be a little erratic on occasion as well. Manager Setien will feel as though he can refine these rough edges in the player's game, though.
What Real Betis potentially have on their hands is a complete midfield player. Carvalho has the attributes to do it all, and he can get even better playing at a higher level. Real Betis will hope to see the Portuguese make this exciting progression in the next chapter of his career.