The 2018 MercedesCup was a men's tennis tournament played on outdoor grass courts.

It was the 41st edition of the Stuttgart Open, and part of the ATP World Tour 250 series of the 2018 ATP World Tour.

First-seeded Roger Federer regained the ATP no.

1 singles ranking by reaching the final.

Roger Federer defeated Milos Raonic, 6–4, 7–6(7–3) Philipp Petzschner / Tim Pütz defeated Robert Lindstedt / Marcin Matkowski, 7–6(7–5), 6–3 The following players received wildcards into the singles main draw: The following players received entry from the qualifying draw: The following player received entry as a lucky loser: The following pairs received wildcards into the doubles main draw: