Spokesman Josh Earnest says the musicians are performing at Obama's annual Independence Day event for "military heroes."
Obama and his wife, Michelle, welcome military families each year for a barbecue, concert and view of the fireworks on the National Mall.
Both musicians are Obama favorites. The president once chose Lamar over Drake in a hypothetical rap battle. Obama also named Lamar's "How Much a Dollar Cost" as his favorite song of 2015.
Monae was a guest at a White House state dinner in May. She also has backed White House efforts on voter registration, gun control and changes to the criminal justice system.