Schools, churches and voluntary groups will be among those invited to apply for funding to mark the occasion.
The Borders Railway Celebration Fund will offer grants of a few hundred pounds up to a maximum of £2,500.
It will also be used to fund railway-themed improvements to public-spaces, play parks and gardens.
Scottish Borders Council leader David Parker said the scheme will operate in a similar way to the Queen's Diamond Jubilee Fund.
"We know that many communities wish to put on special events to commemorate and celebrate the arrival of the Borders Railway and this fund will assist them to do this."
He added: "We have worked hard to make the fund as flexible and as straightforward as possible and I hope that many Borders communities will apply and be involved in the celebrations.
"Although grants will typically be between a few hundred pounds and £2,500, we are very happy to work with communities to access additional funding for unique events or projects that will create a lasting legacy of the return of the Borders Railway."
Applications to the fund can be downloaded here and they must be submitted before 15 December, with projects having to be completed by 31 March 2016.
The Borders Railway will connect Tweedbank with Edinburgh and is scheduled to open in September.
A £50,000 fund has been set up to help communities lay on concerts and street parties to celebrate the return of the Borders Railway.