Armando Pace, 56, who often attacked corruption among politicians and the illegal drug trade in Digos City, was shot in the neck and chest by an assailant on a motorcycle driven by another man, police said.
The assailants, who were tailing Pace after he left radio station dxUM Radyo Ukay, drove alongside his motorcycle and fired at him along Rizal Avenue in full view of many people, police said.
The two men escaped and no one has claimed responsibility for the attack.
Police said the killing could have been "a personal or work-related crime."
Acting station manager Ramon Sibya said he was unaware of any threats against Pace, but said the broadcaster had a string of libel cases filed against him by politicians, businessmen and others before he joined the station eight months ago. Sibya said he was told by Pace that most of them had been dismissed.
Pace was the ninth journalist killed in the country this year and the 82nd since 1986, based on a count by a media watchdog.
He said Pace was not an employee but bought radio air time from the station and obtained his own radio commercials.