The 2019 Estoril Open (also known as the Millennium Estoril Open for sponsorship purposes) was a professional men's tennis tournament played on outdoor clay courts.

It was the fifth edition of the Estoril Open, and part of the ATP Tour 250 series of the 2019 ATP Tour.

The event took place at the Clube de Ténis do Estoril in Cascais, Portugal, from April 29 through May 5, 2019.

[1] The following players received wildcards into the singles main draw: The following player received entry as a special exempt: 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 pairs received entry as alternates: