The British film-maker, who is the younger brother of producer Ridley Scott, was seen parking his car on the Vincent Thomas Bridge and jumping into the water below at about 12:30pm local time.
The 68-year-old's body was recovered by divers around four hours later after sonar equipment was used to locate it in the murky water. His death is not being treated as suspicious.
"I can confirm that Tony Scott has passed away. The family asks that their privacy is respected at this time," Scott's spokesman, Simon Halls, said in a statement.
Scott, known for wearing his trademark red baseball cap, directed Hollywood blockbusters such as Top Gun, Days of Thunder and Beverly Hills Cop II.
US Coast Guard Lt. Jennifer Osburn told local newspaper The Daily Breeze that a suicide note was found inside Scott's black Toyota Prius.
The vehicle was parked on one of the eastbound lanes of the bridge which spans San Pedro and Terminal Island.
Members of the public alerted emergency services after seeing Scott get out of his car and jump from the bridge soon afterwards.
The director, originally from North Shields, lived in Beverly Hills and was married to the actress Donna Scott, with whom he had twin sons.
He ran Scott Free Productions with his brother and the pair were working on a film called Killing Lincoln.
There had been reports that Scott and Tom Cruise were working on a sequel to Top Gun.
Ridley Scott's film Prometheus was one of 2012's summer blockbusters.
His film Gladiator won him the best picture Academy Award in 2000.
While his brother Tony was never nominated for any Oscars his populist action films have been watched by millions of people.
Director Ron Howard paid tribute to Scott, writing on Twitter: "No more Tony Scott movies. Tragic day."
Film director Duncan Jones, who directed Moon and Source Code, wrote: "Just heard about Tony Scott news. Horrible... Tony was a truly lovely man who took me under his wing & ignited my passion to make films."
He added: "Awww Tony. Wish you had felt there was a way to keep going. What a sad waste. My thoughts go out to his wife and beautiful children."
Other films produced by Scott included True Romance, Crimson Tide, Enemy Of The State and Man On Fire.