Jan Mertl (born 3 January 1982) is a Czech former tennis player who competed mainly on the ITF Futures Tour and ATP Challenger Tour.

On 23 July 2007, he reached his highest ATP singles ranking of 163.

[1] Mertl made his ATP main draw debut at 2016 Swiss Open Gstaad, defeating Yann Marti to score his first ATP-level win.

Mertl is the coach of Czech WTA player Markéta Vondroušová.

This biographical article relating to Czech tennis is a stub.