Council Executive approved plans to extend the urban boundary of the town to improve road safety at the new residential development at Standhill South near Armadale Academy.
A statutory procedure will now take place over reducing the stretch of the A89 from 50mph to 30mph, to allow anyone with concerns the opportunity to raise them.
Police Scotland and local councillors have indicated their support for the proposals.
Leader of West Lothian Council Lawrence Fitzpatrick said: "Armadale is a growing community and it's vital we take appropriate steps to support the ongoing development.
"Extending the urban boundary of the town and the 30mph limit is a sensible decision to provide a safer traffic environment for all users and support the expansion of the town.
"Anyone who has any comments to make regarding the proposals will have their chance during the statutory process."