Kai Wagner

Kai Harley Wagner (born 15 February 1997) is a German professional footballer who plays as a left-back for the Philadelphia Union of Major League Soccer.

SSV Ulm
Ahead of the 2015–16 season, Wagner signed his first professional contract at 18 years old with SSV Ulm competing in the Oberliga Baden-Württemberg, the fifth tier of German football. Wagner made 32 appearances and scored one goal, helping earn SSV Ulm the championship title and promotion to the fourth tier Regionalliga.

Schalke 04
In summer of 2016, Wagner secured a transfer to Schalke 04 II competing in the Regionalliga West, the fourth tier of German football.

Würzburger Kickers
In June 2017, Wagner secured a transfer to Würzburger Kickers competing in the 3. Liga, the third tier of German football after being relegated at the conclusion of the 2016–17 season.

Philadelphia Union
In February 2019, Wagner signed with Major League Soccer club Philadelphia Union for an undisclosed transfer fee. Wagner would emerge as one of the best left backs in MLS, contributing 30 appearances and 8 assists in his first season with the Union.

The 2020 season improved on the 2019 season, despite the disruptions of the COVID-19 pandemic, Kai contributed to the Union's advancing to the semi-finals of the MLS is Back Tournament including his first goal for the Union in a 2–1 win over Inter Miami CF. The Union finished the season with the best league record earning the team's first trophy, the 2020 Supporters' Shield. Wagner contributed 14 starts, one goal, and two assists in the Union's championship season.

In January 2021, Wagner signed a new contract with the Union through the 2022 season, with an option for 2023. In August 2021, Wagner was selected to the 2021 MLS All-Star Game versus the Liga MX All-Star team.

On 7 November 2023, Wagner was suspended for three games by Major League Soccer for violating the league's anti-discrimination policy. The violation happened on 28 October 2023, during a match against New England Revolution when Wagner called an opposing forward, Bobby Wood, a slur considered racist towards Asian people.

On January 11, 2024, the Union re-signed Wagner to a new three-year contract that would keep him in Chester through the 2026 MLS Season. This contract included a club option for the 2027 MLS season as well. This signing comes after months of speculation that Wagner would not return to the Union, and instead head overseas to play in Europe.

Honours
SSV Ulm
 * Oberliga Baden-Württemberg: 2015–16

Philadelphia Union
 * Supporters' Shield: 2020
 * MLS Cup runner-up: 2022

Individual
 * MLS All-Star: 2021, 2022
 * MLS Best XI: 2022