The train operator has pledged to press every available carriage into service, but warned Festival-goers that trains would still be "extremely busy".
Extra carriages will also be provided on services to Fife, Dundee and Perth.
Trains on the main Glasgow line via Falkirk High will run with seven or eight carriages compared to a maximum of six last year.
ScotRail said the 29 per cent increase in carriages over the course of the day was the equivalent of more than 60 extra trains a day during the Festival.
There will be later trains on the route as in previous years, leaving Edinburgh Waverley at 0003 and 0033 from 3-26 August, but this time they will also stop at Haymarket .
There will also be 11 per cent more carriages than last year on Fife trains, and extra carriages on the Borders Railway.
Extra late-night trains will also be laid on at weekends to Bathgate, Fife, Dundee, and North Berwick, with a bus connection for Dunbar.
An additional service will run again from North Berwick to Edinburgh for 11 nights for passengers returning the Fringe by the Sea events.
ScotRail Alliance chief operating officer Angus Thom described the Edinburgh Festivals as "one of the great highlights of the Scottish cultural calendar".
He said: “As with previous years, we’ll be doing all we can to keep things running smoothly.
"As well as running extra trains, including late-night trains, every available carriage will be used to get people to and from Edinburgh.
“Trains are going be extremely busy.
"We’re encouraging everyone visiting the capital to plan their journey in advance by using our app or the ScotRail website, and to buy a ticket before they board.”
Edinburgh-Glasgow via Falkirk High - 0003 and 0033 from from 3 to 26 August.
Edinburgh-Glasgow train via Bathgate - 0011 on Friday nights and 0009 on Saturday nights from 3 to 25 August.
Edinburgh-Glenrothes via Dunfermline - 2359 on Friday nights from 3 to 24 August.
Edinburgh-Dundee service - 2352 on Friday and Saturday nights from 3 to 25 August.
Edinburgh-North Berwick - 0010 on Friday and Saturday nights from 3 to 25 August.
North Berwick-Edinburgh - 0003 from 3 to 12 August.