The change precedes an expected move by the public television broadcaster to transform itself into the country's first free 24-hour TV station.
Channel 9 is counting on the programme overhaul to lure more viewers and raise ad revenue by 50 per cent.
Effective this month, the broadcaster will add more variety shows, sports programmes, game shows, drama series and movies to its schedule, particularly between 6:30pm and midnight on weekdays, said Jarujit Nawapan, who heads the international relations section of the Mass Communication Organisation of Thailand, Channel 9's operator.
A number of high-profile documentaries, from BBC Wild Life, National Geographic and Animal Planet, would also be introduced, she said.
Channel 9's bid for a larger slice of the pie parallels moves at competitor iTV, which recently said it would step up news delivery and enliven entertainment offerings under the twin concepts of "speed and spice". The broadcaster's move also due to come into effect this month.
Competition between the two channels for the number three slot among Thailand's viewers adds a new dimension to an industry long dominated by channels 3 and 7.
In a defensive move, Channel 3 operator BEC World has said it would upgrade news coverage and offer more sports programmes to prevent audiences from shifting to other channels. However, the two still have some way to go before posing a serious threat to the long-time industry leaders.
Television is by far the largest advertising medium in Thailand, accounting for 61 per cent of last year's total 61.2 billion baht adspend, and boasting a 93 per cent penetration rate in Bangkok and 87 per cent nationwide.
In addition to the programme revamp, Channel 9 also plans to raise ad rates this month for its 9pm to midnight slots. The increase is expected to help pay for 104 new staff, from news reporters to marketing executives.
The broadcaster currently has the lowest ad rates among the four, at around 110,000 baht (about US$2,600) per minute, compared to iTV's 250,000 baht and Channel 7's 280,000 baht.
THAI TV - HOW THEY STACK UP
Channel Share of Share of
ad dollars audience
Channel 7 27% 42%
Channel 3 26% 31%
Channel 9 12% 8%
iTV 12% 8%
Source: Nielsen Media Research