Regular driver training services will begin on Tuesday, ahead of the planned launch of the first passenger services in September.
The train left at 7.30am for the final stop in the Borders at Tweedbank, before turning around and making the same journey again at noon.
Rail campaigners last week criticised the decision to launch the service with rolling stock made up almost entirely of old carriages blasted as being among the most unreliable in the Scotrail fleet.
The original Waverley Line between Edinburgh and Carlisle was ripped up in 1969. The new line between the capital and Tweedbank will cost £294m to build, using much of the same route, including original bridges and viaducts.