The 22-year-old centre-back arrives as one of Marco Rose's key additions, following the recent signing of Alvaro Rodríguez, and fills the void left by the departure of Marcos Senesi, who joined Tottenham after his contract expired.
Silva leaves Benfica after an outstanding spell in Lisbon, where he amassed more than 235 senior appearances despite his young age. During that time he won six major honours, earned recognition as the Primeira Liga's best defender in the 2022-23 season and established himself as one of Portugal's brightest defensive talents.
At international level, Silva has won 20 caps for Portugal, featuring at the 2022 FIFA World Cup, Euro 2024 and the successful 2025 UEFA Nations League campaign, although he was not included in the squad for the 2026 World Cup.
Bournemouth identified Silva as their preferred defensive recruit after targeting a left-sided, ball-playing centre-back capable of replacing Senesi. Club officials also believe his experience in domestic and European competition, coupled with a proven winning mentality, makes him an ideal fit for the squad.
President of Football Operations Tiago Pinto said the club had admired Silva for some time.
"Antonio is a player we have admired for a long time and we're delighted to welcome him to AFC Bournemouth.
"Despite being only 22, he has already built an outstanding level of experience at one of Europe's biggest clubs, playing consistently in domestic, European and international competitions. Those experiences have helped shape him into a defender with real maturity and leadership qualities.
"He is ambitious, has a proven winning mentality and knows what it takes to compete for trophies. Those are the characteristics we want to bring into this football club as we continue to build a squad capable of competing at the highest level."
Silva is eager to begin life on the south coast and believes Bournemouth can continue to progress.
"I am very happy to be here. It's a pleasure to play for Bournemouth and in the Premier League. I can't wait to start the season with my teammates, and I'm excited to be here.
"The mentality is always to win. I will try my best, and I will play for the fans. We have everything here that helps us perform on the pitch, and I can't wait to get started."
Bournemouth's preparations for the new campaign have been mixed after forward Junior Kroupi was ruled out for around three months with a foot injury, but the arrival of Silva represents a significant boost ahead of their Premier League opener away to Manchester City on 23 August.
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