The Oscar-winning director and producer received the bachelor's degree in film and electronic arts from California State University at Long Beach, where he enrolled in 1965, but left three years later without finishing his studies.
"I wanted to accomplish this for many years as a thank-you to my parents for giving me the opportunity for an education and a career, and as a personal note for my own family - and young people everywhere - about the importance of achieving their college education goals," he said.
"But I hope they get there quicker than I did," he added.
"Completing the requirements for my degree 33 years after finishing my principal education marks my longest post-production schedule."
As Spielberg, 55, walked across the stage wearing a cap and gown, the college band struck up with theme tune from Indiana Jones - the film trilogy he directed - and he was given a standing ovation.
Later the grey-haired director posed for pictures with his fellow honourees - some more than 30 years his junior - on the campus lawn.
Incognito
After re-enrolling to the college a year ago, Spielberg topped up his credits, the points necessary to gain an American undergraduate degree.
He registered under a pseudonym, and his decision to get the degree was kept quiet until recently.
Unable to attend normal classes, the director wrote essays, worked on independent projects and consulted with professors to receive his degree in film and electronic arts, according to his spokesman, Marvin Levy.
To pass the advanced filmmaking class exam Spielberg submitted his epic, Schindler's List.
"I think that counts as an advanced... polished film," said Sharyn Blumenthal, directors of the school's Films and Electronic Arts Department.
Records broken
In 1969, Spielberg made a 22-minute short film Amblin, which was shown at the Atlanta Film Festival.
This led to a long-term contract with a Hollywood studio.
But he sealed his fame with Jaws and went on to direct ET, Schindler's List and Saving Private Ryan among a galaxy of other hits.
His Raiders of the Lost Ark and Jurassic Park series have broken box office records.
The director has several honorary degrees and three Oscars - two for Schindler's List and another for Saving Private Ryan.
He also co-founded the studio DreamWorks SKG with partners David Geffen and Jeffrey Katzenberg.
Spielberg's sci-fi adventure Minority Report is released on 21 June, and he recently finished filming the Leonardo DiCaprio and Tom Hanks crime drama Catch Me If You Can.