The Uruguay international will undergo a medical in the coming hours before being placed at the disposal of head coach Claudio Giráldez, with a first training session alongside his new teammates scheduled for Saturday morning — the squad has Friday off.
A first inclusion in the matchday squad, for Monday's game against Getafe, has not been ruled out.
Cáceres becomes the sixth and final signing of Celta's transfer window, joining a group of arrivals that also includes Aleix Febas, Javi Galán, Driouech, Abdoulaye Faye and Altay Bayindir, the last two on loan from Bayer Leverkusen and Manchester United respectively.
The 27-year-old centre-back has signed a four-year contract running until June 2030, in a deal reported to be worth around €5m, or roughly $8m, according to Mexican outlets covering the sale.
He leaves Club América having made 209 appearances across six and a half seasons in Liga MX, amassing close to 17,000 minutes and winning three league titles — the Clausura 2023, Apertura 2023 and Clausura 2024 — along with the Campeón de Campeones and Concachampions.
Cáceres came through the youth ranks at Liverpool Montevideo before making the move to Mexico in 2020, and has been a full Uruguay international since 2022, featuring at the 2024 Copa América, where his country finished third, and starting for Marcelo Bielsa's side at this summer's World Cup.
His arrival gives Giráldez fresh options at the back after a difficult start to the season that has left Celta Vigo still searching for their first win, with the Galician club hopeful the experienced defender can settle quickly and add the stability the squad has lacked in recent weeks.
The deal caps a busy summer of business in Vigo, which also included the arrivals of Ferrán Jutglà from Club Brugge and Ilaix Moriba from RB Leipzig earlier in the year, as Celta prepare for a season that will include their first Europa League campaign in some time following a sixth-place finish in LaLiga last term.
Cáceres is expected to compete immediately for a starting berth in the heart of Celta's defence, with his experience at international level viewed internally as a valuable addition to a squad now balancing domestic and continental commitments.