The contract has been awarded to the Belfast-based Macmillan Media, which has offices in London and Glasgow. STV has supplied GMTV with its news since the breakfast channel took over from TV-am in 1993. The newsroom produces three bulletins of about three minutes each at 6:40am, 7:10am and 8:10am.
But after contract discussions, the London-based GMTV has gone for what is thought to be a cheaper option. Macmillan already has the contract to provide the GMTV local opt-outs for Northern Ireland.
STV newsroom staff were told of the decision earlier this week. It is not yet known if any jobs will be affected. A spokesman for STV said: "We are surprised and disappointed with GMTV's commercial decision to choose a cheaper alternative provider of Scottish news bulletins which is based in Northern Ireland and is not as well-resourced as our own news operation."
The broadcaster said its flagship Scotland Today and North Tonight bulletins would not be affected by the loss of the breakfast contract. STV would not disclose the value of the contract to supply GMTV.
The news will be a disappointment to STV in the same week it emerged that the broadcaster had poached the respected filmmaker Alan Clements to be its new director of television.
Mr Clements's company, IWC, was bought by RDF media, the maker of shows such as Ladette To Lady and Wife Swap, in a deal worth 14 million in 2005.
Mr Clements is negotiating his exit from RDF and is expected to join his new employer later this year.
Macmillan Media specialises in corporate video production and offers media training courses led by the former BBC War correspondent and ITN News at Ten reporter Michael Macmillan.