Borderlands: The Handsome Collection and Sonic Mania will be free to download from Tuesday June 4.
Normally priced at $59.99/£44.99, Borderlands: The Handsome Collection includes Borderlands 2, Borderlands: The Pre-Sequel and all DLC for both titles.
Released in 2017, 2D platformer Sonic Mania normally costs $19.99/£15.99.
As of March 2019, PlayStation Plus had 36.4 million subscribers, according to Sony.
The latest membership count was announced as the PlayStation division recorded increased sales and operating income for its fiscal year ended March 2019.
The company also said PlayStation 4 sales stand at 94.2 million units.