Early career After retiring, Walter began his coaching career with
Karlsruher SC in 2006, being an assistant of
Markus Kauczinski in the under-19 team. He took over the under-15s in the following year, before moving to the under-17s in 2013, and to the under-19s in 2014. On 7 July 2015,
Bayern Munich paid Karlsruhe a
€ 200,000 fee to sign Walter, who was named manager of their under-17 team. On 17 May 2017, he was appointed manager of Bayern's
reserve team.
Holstein Kiel On 24 May 2018, Walter was appointed manager of
2. Bundesliga side
Holstein Kiel, replacing departed
Markus Anfang. His first professional match in charge occurred on 3 August, a 3–0 away win over
Hamburger SV. Walter led Holstein Kiel to a 6th-place finish in the
2018–19 2. Bundesliga, eight points shy of a play-off qualification.
Stuttgart In June 2019, Walter became the new head coach of
VfB Stuttgart also in the second division. He was sacked on 23 December, despite having his team on the third position.
Hamburger SV On 25 May 2021, after more than a year without a club, Walter was named the new head coach of fellow 2. Bundesliga side Hamburger SV. He lost promotion in the play-offs in his first two seasons, and was sacked in February 2024.
Hull City On 31 May 2024, Walter was appointed head coach of
EFL Championship side
Hull City on a three-year deal. He managed his first competitive game with the Tigers on 10 August 2024, the opening fixture of the
2024–25 season, a 1–1 home draw with
Bristol City. Having gone 1–0 down with six minutes to go,
Óscar Estupiñán scored the club's first goal under Walter's stewardship, a well-converted penalty in added-time. On 27 November 2024, with the club sitting in 22nd position and without a win in 9 games, Walter was relieved from his role as manager following a 2-0 defeat to
Sheffield Wednesday, despite chairman
Acun Ilıcalı stating he would remain in the job no matter the outcome of the game.
Holstein Kiel On 24 February 2026, Walter was appointed manager of
2. Bundesliga side
Holstein Kiel, replacing departed
Marcel Rapp. ==Managerial statistics==