The unnamed man started firing shots and set a table on fire in the gaming area of Resorts World Manila in the early hours of Friday.
Security forces said a manhunt ended with the gunman lying in bed in a hotel room covered with a blanket and setting himself on fire.
At least 50 people were taken to hospital. Police said the incident was not terror-related.
“He lay down on the bed, covered himself with a thick blanket, apparently poured petrol on the blanket and burned himself,” national police chief Ronald Dela Rosa said on Friday.
Resorts World Manila said in a statement reported by GMA News that the man also shot himself after setting himself on fire, and that he was found dead around 07:00 local time (23:00 Thursday GMT).
It called the casino shooting a “cowardly act of a deranged mind”.
Manila police chief Oscar Albayalde told reporters that it was “a simple robbery and most likely it was done by a demented person”.
Authorities said the man entered the casino shortly after midnight and began shooting at television screens.
He also set a gaming table on fire, and filled a backpack with gambling chips worth 113m Philippine pesos (£1.7m, $2.3m).
The incident sparked a stampede as panicked crowds fled the scene. More than 50 people were injured, including a security guard who accidentally shot himself, said Mr Dela Rosa.
The man later fled to the hotel section of the complex, leaving behind the backpack.
Police initially said they had cornered the gunman in a hotel room and killed him, but later said he killed himself. (Courtesy BBC)