The 2018 Marburg Open was a professional tennis tournament played on clay courts. It was the ninth edition of the tournament which was part of the 2018 ATP Challenger Tour. It took place in Marburg, Germany between 2 and 8 July 2018.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 Estonia | Jürgen Zopp | 107 | 1 | |
| Yannick Hanfmann | 111 | 2 | ||
 Bolivia, Plurination;al State of | Hugo Dellien | 120 | 3 | |
 Brazil | Thiago Monteiro | 132 | 4 | |
| Pedro Sousa | 135 | 5 | ||
| Brazil | Rogério Dutra Silva | 136 | 6 | |
 Russian Federation | Alexey Vatutin | 137 | 7 | |
| Henri Laaksonen | 142 | 8 |
The following players received wildcards into the singles main draw:
The following player received entry into the singles main draw as a special exempt:
The following players received entry from the qualifying draw:
See main article: article and 2018 Marburg Open – Singles.
Juan Ignacio Londero def. Hugo Dellien 3–6, 7–5, 6–4.See main article: article and 2018 Marburg Open – Doubles.
Fabrício Neis / 
David Vega Hernández def. Henri Laaksonen / Luca Margaroli 4–6, 6–4, [10–8].
