A birth certificate released Friday shows the couple's daughter Isabelle Amarachi Asomugha was born around 5 p.m. on April 21 in Los Angeles. The parents haven't announced the baby publicly. Washington's publicist Amanda Silverman said no statement was available.
Washington is the Emmy-nominated star of the ABC series "Scandal." The show's third season was cut short after the 37-year-old actress became pregnant.
Asomugha, a former cornerback with the Oakland Raiders, Philadelphia Eagles and San Francisco 49ers, announced his retirement last year.
The birth was first reported Friday by celebrity website TMZ.