On 13 June 2013, Bayer Leverkusen confirmed Son's transfer for reportedly €10 million, which was the highest transfer fee in club history at the time.
He agreed to a five-year deal with the team.
Son adjusted quickly to his new club in the pre-season, scoring three goals in his first three appearances for the team in exhibition matches (against 1860 Munich, Udinese and KAS Eupen respectively).

On 9 November 2013, Son scored a hat-trick for Leverkusen in a 5–3 win against his former club Hamburgers SV.
On 7 December, Son scored a crucial goal against Borussia Dortmund to put his club just four points off the summit of the Bundesliga.
On 10 May 2014, Son scored another goal against Werder Bremen ensuring his team a spot for the 2014–15 UEFA Champions League.
He finished the 2013–14 season with 12 goals in 43 matches.

Son scored a hat-trick against VfL Wolfsburg on 14 February 2015, in a 4–5 defeat, scoring when they were losing 0–3.
He finished the 2014–15 season with 17 goals in 42 matches.

Son started the 2015–16 season with Bayer Leverkusen.
He made a league appearance and a Champions League qualifying match.
On 13 June 2013, Bayer Leverkusen confirmed Son's transfer for reportedly €10 million, which was the highest transfer fee in club history at the time. He agreed to a five-year deal with the team. Son adjusted quickly to his new club in the pre-season, scoring three goals in his first three appearances for the team in exhibition matches (against 1860 Munich, Udinese and KAS Eupen respectively).
On 9 November 2013, Son scored a hat-trick for Leverkusen in a 5–3 win against his former club Hamburgers SV. On 7 December, Son scored a crucial goal against Borussia Dortmund to put his club just four points off the summit of the Bundesliga. On 10 May 2014, Son scored another goal against Werder Bremen ensuring his team a spot for the 2014–15 UEFA Champions League. He finished the 2013–14 season with 12 goals in 43 matches.
Son scored a hat-trick against VfL Wolfsburg on 14 February 2015, in a 4–5 defeat, scoring when they were losing 0–3. He finished the 2014–15 season with 17 goals in 42 matches.
Son started the 2015–16 season with Bayer Leverkusen. He made a league appearance and a Champions League qualifying match.
Son Heung-min