The company has blamed the high cost of connecting to the grid for its decision which confirms an earlier announcement after it failed to win a £15 million contract from National Grid.
It has also decided not to replace Cockenzie in East Lothian with a gas-fired power station.
Longannet, which opened in 1972, employs 230 staff and is one of the biggest coal-fired power stations in Europe. It was also the site of the last deep-mined pit in Scotland. The power station was scheduled for closure in 2020.
Scotland’s power generation will now rest on SSE’s gas-fired power station at Peterhead – which won the National Grid work from Longannet – and EDF’s two nuclear stations at Hunterston and Torness, as well as the renewables sector which is taking a greater share of electricity needs.
Neil Clitheroe, chief executive of retail and generation at Scottish Power, said: “We have explored every potential option to keep the station open, and we still maintain that Longannet could continue generation in to the next decade under the right economic conditions.
“Our main focus now is consulting with staff to ensure we find the best outcomes possible for all of the 236 impacted employees, many of whom have spent their entire career at the station.
“We would like to thank everyone at the station for their professionalism and continued commitment, and we know that the last few months have been very difficult.”