The 29-year-old left-footed centre-half joins from a Bournemouth side he helped qualify for European football for the first time in the club's history, finishing sixth in the Premier League under Andoni Iraola — now, of course, Tottenham's closest rival's new manager at Liverpool.
He made 128 appearances for Bournemouth in all competitions. In his final season he was one of the most productive defenders in the division — according to Spurs' official announcement, no outfield player in the Premier League completed more long passes (182), and no centre-back produced more assists. He also ranked in the top three league-wide for most interceptions, most blocks and most clearances.
Senesi arrives with significant European experience. Born in Concordia, Argentina, he began his career at San Lorenzo before joining Feyenoord in 2019. He played in European competition in each of his three seasons in Rotterdam, including 12 of Feyenoord's 13 matches as they reached the inaugural UEFA Europa Conference League Final in 2022. He joined Bournemouth later that summer for approximately €15 million.
He has three caps for Argentina at senior level.
Roberto De Zerbi was direct in his assessment of what the signing provides.
"Marcos' experience, quality on the ball, and competitive edge will strengthen us defensively, as well as giving us flexibility in formation. He's comfortable playing in a possession-based team, reads the game very well and has the personality to thrive in a demanding environment.
"I also love his mentality and desire to keep improving and I'm looking forward to working with him and seeing the big contribution he can make to the team."
Sporting director Johan Lange described the signing as precisely the type of profile the club was targeting.
"Marcos is a defender who brings a combination of quality, intelligence and leadership to our squad. His experience at the highest level, his composure in possession and his desire to compete for every ball make him an excellent fit for the way we want to play.
"We are delighted to welcome him to the Club and believe this is the perfect place for him as he enters a great stage in his career."
Senesi himself spoke with unambiguous conviction about his reasons for choosing Spurs.
"It's a very special feeling to be a Tottenham Hotspur player. From the first moment, the Club has shown why they want me and how much they want me to be a part of what they are building. Every time I step on the pitch, I will do my best to make the fans proud and to take the Club back to the place it belongs. I want to win things with Tottenham and will do everything I can to make that happen."
He follows Andy Robertson in through the door this summer. Talks over Gleison Bremer of Juventus and Micky van de Ven's contract situation remain ongoing.
The free transfer is the model De Zerbi has outlined for the window. The quality, in Senesi's case, is beyond question.