Air Force United In January 2018, Flottmann left
Sydney FC due to lack of game time and signed with
Thai League 2 club
Air Force United. He played 17 matches during his season at Air Force United.
Return to Sydney FC Flottmann returned to his youth club,
Sydney FC in July 2019, signing a 2-year senior contract. He made his debut on 29 December 2019 against
Melbourne City, coming on as a substitute to replace
Adam Le Fondre in the 88th minute. On 28 April 2021, he was loaned to
Brisbane Roar for a couple of weeks to provide injury cover for
Tom Aldred. In July 2021, Sydney FC announced that they had released Flottmann.
NorthEast United In November 2021, Flottmann signed with
Indian Super League club
NorthEast United. He made his debut against
Kerala Blasters FC on 25 November. He scored his first goal on 17 December in a 2–0 win against
East Bengal.
Seongnam FC On 1 February 2023, Flottmann joined
K League 2 club
Seongnam FC. He played in 22 matches and scored 2 goals
DPMM FC On 9 April 2024, Flottmann was signed by
Brunei DPMM FC for the
2024–25 Singapore Premier League season. Flottmann suffered a
ruptured anterior cruciate ligament in a friendly match a month later which ultimately ended his stint at the Bruneian club.
APIA Leichhardt On 20 July 2025,
National Premier Leagues NSW side
APIA Leichhardt FC announced the signing of Flottmann. His stay with the club from
Sydney ended in early January 2026.
Avondale Flottmann subsequently signed for
Avondale FC, reigning premiers of the
NPL Victoria for the
2026 season. ==Career statistics==