Single bus fares across Renfrewshire will be capped at £2 from Monday 7th September.
The cap will be introduced throughout the Strathclyde Partnership for Transport area.
It will cover journeys in Glasgow, Renfrewshire, Ayrshire, Dunbartonshire, Lanarkshire and Inverclyde.
The Scottish Government announced the expansion as part of its Programme for Government.
A £2 bus fare cap is already in place in the Highlands and Islands.
The Scottish Government has pledged to introduce the cap throughout Scotland by the end of the current parliamentary term. No date has been announced for the national rollout.
Tom Arthur, SNP MSP for Renfrewshire West and Levern Valley, said: “I am delighted today’s Programme for Government saw the First Minister John Swinney announce that the £2 bus fare cap will come into effect across the West of Scotland, including Renfrewshire West and Levern Valley, on Monday.”
Ross Greer, co-leader of the Scottish Greens and a West Scotland MSP, welcomed the expansion but criticised the timescale for introducing the cap elsewhere.
He said: “Most people in Scotland are going to have to wait up to five years before they get the two pound bus fare cap in their area. This is something the Scottish Greens brought in in the Highlands and Islands at the start of the year. It’s been a huge success, saved people a fortune, much like the free bus passes we brought in for young people.
“The SNP said that we’re going to roll out across the rest of the country and from next Monday that is going to be the case across the west of Scotland, but they also said today it might be 2031 before some parts of Scotland get this. Compare that to England where it will start in January across the whole country. People need help with the cost of living now.
“The cost of getting a bus needs to come down so the Greens are going to fight to make sure we can introduce that two pound fare cap as soon as possible and move towards free bus travel for everybody as quickly as we can.”