The 20-year-old goalkeeper has been playing at Borussia Dortmund since July 2016, initially for the youth team and since 2019 as a professional. He has yet to play a competitive game for the first team. As of 30.6.21, he has played 31 games in the Regionalliga and was part of the U23s side who secured promotion into the 3. Liga.

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 and U19s. In February 2019, he was called up to the first team squad for the first time for the cup game against Bremen.

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 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 bronze medal. The English newspaper "The Guardian" listed him among the 60 most talented youngsters born in 2001.

He won the U17 German Championship in 2018 and lifted the U19 title the following year. However, the "number 1" missed the 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.