2021 Open de Oeiras IV – Doubles

Hunter Reese and Sem Verbeek were the defending champions but chose not to defend their title.

Jesper de Jong and Tim van Rijthoven won the title after defeating Julian Lenz and Roberto Quiroz 6–1, 7–6(7–3) in the final.

Seeds
• # 🇺🇸 Evan King / Gonçalo Oliveira (quarterfinals)

• # 🇫🇷 Sadio Doumbia / 🇫🇷 Fabien Reboul (first round)

• # 🇩🇪 Dustin Brown / 🇦🇹 Tristan-Samuel Weissborn (quarterfinals)

• # 🇵🇱 Karol Drzewiecki / 🇪🇸 Sergio Martos Gornés (first round)