On 4 January 2017, Lenglet moved to Spain, signing a deal with La Liga side Sevilla FC until 2021.
The transfer fee paid to Nancy was €5 million.
He was brought in to replace compatriot Timothée Kolodziejczak, who had joined Borussia Mönchengladbach.

He made his debut for the Andalusians eight days later in a 3–3 home draw with Real Madrid in the last 16 of the Copa del Rey (6–3 aggregate loss).
On 15 January he made his league bow against the same opponents in a 2–1 win at the Ramón Sánchez Pizjuán Stadium that ended their 40-match unbeaten run in all competitions.
He played 17 of their league fixtures in the second half of the season.

On 19 August 2017, Lenglet scored his first goal for Sevilla, opening a 1–1 home draw against RCD Espanyol in the first game of the new season; whether or not it crossed the line became a matter of controversy after the game.
He scored his first goal in European competition on 1 November, heading Éver Banega's cross to open a 2–1 home win against FC Spartak Moscow in the group stage of the UEFA Champions League.
Having been part of the Sevilla side that kept a clean sheet against Manchester United in the round of 16 first leg, ESPN FC put Lenglet into their Champions League Best XI.
On 4 January 2017, Lenglet moved to Spain, signing a deal with La Liga side Sevilla FC until 2021. The transfer fee paid to Nancy was €5 million. He was brought in to replace compatriot Timothée Kolodziejczak, who had joined Borussia Mönchengladbach.
He made his debut for the Andalusians eight days later in a 3–3 home draw with Real Madrid in the last 16 of the Copa del Rey (6–3 aggregate loss). On 15 January he made his league bow against the same opponents in a 2–1 win at the Ramón Sánchez Pizjuán Stadium that ended their 40-match unbeaten run in all competitions. He played 17 of their league fixtures in the second half of the season.
On 19 August 2017, Lenglet scored his first goal for Sevilla, opening a 1–1 home draw against RCD Espanyol in the first game of the new season; whether or not it crossed the line became a matter of controversy after the game. He scored his first goal in European competition on 1 November, heading Éver Banega's cross to open a 2–1 home win against FC Spartak Moscow in the group stage of the UEFA Champions League. Having been part of the Sevilla side that kept a clean sheet against Manchester United in the round of 16 first leg, ESPN FC put Lenglet into their Champions League Best XI.
Clément Lenglet