The 21-year-old goalkeeper has been playing at Borussia Dortmund since July 2016, initially for the youth team and since 2019 as part of the first team squad. He has yet to play a competitive game for the first team. As of the end of June 2022, he has made 52 appearances in the Drittliga and Regionalliga.

Luca Unbehaun, born and raised in Bochum, started at SC Union Bergen, moved to VfL Bochum as an eight-year-old and joined Borussia Dortmund in 2016, where he won the German championship with both the U17s (in 2018) and U19s (in 2019). However, he missed the U19s final due to a knee injury which required surgery. In June 2021, he was in the BVB goal as the U23s won promotion to the 3. Liga.

Luca Unbehaun has all the attributes a modern goalkeeper needs. He has lightning-fast reflexes and is good on the ball to go with the necessary height (186 cm) and the composure you need in critical game situations. "As a goalkeeper, I want to give off a sense of composure and strong nerves to put my team-mates at ease. I'm a goalkeeper that likes to play and to initiate our attacks in the way that Manuel Neuer or Marc-André ter Stegen do, for example," said the German youth international. His goalkeeping coach at the BVB academy, Marco Knoop, once said: "Luca has strong nerves and is ambitious, but is also down to earth and outgoing. He is a safe pair of hands who puts everyone at ease. His development has been more than positive." In February 2019, he was called up to the first team squad for the first time for the cup game against Bremen.

In the 2018-19 season, Luca Unbehaun became the fourth Black & Yellow in history – after Marc-André Kruska, Sebastian Tyrala and Mario Götze, who received the award twice – to be honoured with the Fritz Walter Medal given to the best youth players. The English newspaper "The Guardian" listed him among the 60 most talented youngsters born in 2001. Since the U15s, he has played in the youth teams for the German national side. He was the starting goalkeeper at the U17 European Championship in 2018 and made his debut for the U20s in September 2020 in the 0-0 draw with Denmark.