In a joint statement, the two broadcasters said Channel i had struggled to attract strong ad revenues in what they described as a small and fragmented market for English-language TV, with little sign of turning around its operations.
Channel i will cease transmission on January 1.
The companies are currently deciding whether to retain any Channel i shows in a scheduling revamp that will also see their Chinese-language channels, Channel 8 and Channel U, repositioned to avoid direct competition.
MediaCorp and MediaWorks have already made interim programming changes to Channel 8 and Channel U ahead of more permanent changes due to be announced in the first quarter of next year. Media agencies expect Channel 8 will concentrate on local dramas, while Channel U will focus on variety.
Channel i had failed to attract a strong audience since launching in 2001 and its closure came as little surprise to the market.
"The only impact could be in terms of future programming offers," said Elaine Quek, general manager of MEC Singapore. "Channel i's existence created competition for content which forced both, especially Channel 5, to provide better quality and more up-to-date programmes."
The two media owners have also announced that about 200 people will be let go from their combined operations, in their first major public statements since announcing a tie-up of their terrestrial TV and free newspaper operations earlier this year.
The majority of affected staff are employed by Singapore Press Holdings, most of whom are within MediaWorks. Of these, 200 will be transferred to MediaCorp, 97 will be absorbed by SPH and 132 will be retrenched.
MediaCorp is also releasing 72 staff as part of a separate staffing review.