The 2021 Hamburg European Open was a combined men's and women's tennis tournament played on outdoor clay courts. It was the 115th edition of the event for the men and the 19th edition for the women, after last tournament being held in 2002. The tournament was classified as a WTA 250 tournament on the 2021 WTA Tour and as an ATP Tour 500 series on the 2021 ATP Tour (called the Hamburg Open). The tournament took place at the Am Rothenbaum in Hamburg, Germany between 6 and 18 July 2021. The event was scheduled a week earlier than the usual late July date to avoid scheduling conflicts with the 2020 Summer Olympics.
This was Ruse's maiden WTA Tour singles title.
<sub>*per team</sub>
The following players received wildcards into the main draw:
The following players received entry from the qualifying draw:
The following players received entry as lucky losers:
The following pairs received wildcards into the doubles main draw:
The following pair received entry using protected ranking:
The following pair received entry from the qualifying draw:
The following pair received entry as lucky losers:
The following players received wildcards into the main draw:
The following players received entry from the qualifying draw:
The following player received entry as a lucky loser:
The following pair received a wildcard into the doubles main draw: