Bueno, 24, who has two international caps, joins the West Midlands club on a five-year contract.
Wolves have also announced the arrival of 18-year-old winger Enso Gonzalez from Paraguayan side Libertad.
He joins on a six-year deal for a fee believed to be in the region of 12m euros (£10m), subject to international clearance and a work permit.
The South American duo are the first two players to join Wolves since Gary O'Neil was appointed as manager earlier this month.
O'Neil also confirmed on Thursday that Portugal midfielder Matheus Nunes is on his way to Manchester City for a reported fee of £53m and that he is hopeful of adding to his squad before Friday's summer transfer deadline.
"The recruitment team are working extremely hard to get a balanced squad. The squad will be in a better place than it was last week by the end of the window," said O'Neil.
Bueno made 102 league appearances for Girona after joining them from Barcelona B in 2019, and spent last season playing in La Liga after the club was promoted from the Segunda Division.
He made his international debut for Uruguay earlier this year in a friendly draw with Japan in Tokyo.
Gonzalez broke into the first team of the Paraguayan Primera Division side in September 2022 and has scored three goals in 23 league games since January.
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