The baby boy was born on January 19, and the news was announced via a statement released by Johnson's management company, reported Us magazine.
"Paulina and I are happy to announce the arrival of our baby boy, who was born in Los Angeles on Monday morning," Johnson, 30, wrote in the statement.
"Both Paulina and the baby are healthy, resting comfortably and in great spirits! We sincerely appreciate the outpouring of love and support we have received and plan to release further details in the coming days!" he added.