The substantial upgrade of Dalmarnock Station, in Glasgow's East End, includes a new entrance, ticket office, lifts and footbridge.
The station is the closest to Games venues the Emirates Arena and Sir Chris Hoy Velodrome and Celtic Park, where the opening ceremony will take place.
Deputy First Minister Nicola Sturgeon officially marked the completion of the project which will benefit the community long after the Games are over.
The station revamp is hoped to be a significant driver for the regeneration of the area the Commonwealth Games is hoped to provide.
The work, which was carried out by Network Rail, has been funded by Transport Scotland, Clyde Gateway, Glasgow City Council and Strathclyde Partnership for Transport.
Ms Sturgeon said: "This station will play host to visitors from all corners of the world and possibly some of the best known sports stars on the planet. It is hugely exciting to see it complete and know what lies ahead.
"The Games is much more than medals - it's a catalyst for regeneration, innovation and for sustainable economic growth and the refurb-ishment of Dalmarnock Station demonstrates this.
"The Games are already providing a massive boost to reviving areas such as the East End of Glasgow and helping communities contribute to Scotland's economic success."
The station was first opened in 1895 and is used by around 80,000 passengers a year. Many more are expected during the Games with thousands of spectators, officials and athletes heading to the arenas.
Glasgow 2014 chief executive David Grevemberg said: "Glasgow 2014 welcomed the completion of the station which will be a key hub at Games time due to its proximity to a number of our venues including Celtic Park, which will host the opening ceremony on July 23 along with the Emirates Arena and Sir Chris Hoy Velodrome, not to mention the adjacent Athletes' Village.
"The work from our partners to transform Dalmarnock Station recog-nises the vital role public transport plays in ensuring a successful Games."