The inflation level increase will push up the cost of a monthly season ticket between Glasgow and Edinburgh by almost £9 to £356, but off-peak fares will remain frozen for a second year.
The annual increases will be lower in Scotland than England, where peak time fares will rise by Retail Price Inflation (RPI) plus one per cent.
That means cross-Border services on key Scotland to London routes along the East and West Coast Main Lines will increase 3.5 per cent.
The ScotRail increases are pegged to last month's RPI, which stood at 2.5 per cent.
The Scottish Government stepped in last year to cap peak time fares at RPI only until the current ScotRail franchise expires in 2015, with additional funding to freeze off-peak fares during 2014 and 2015.
About four in every 10 journeys by ScotRail passengers are taken during off-peak hours.
A ScotRail spokeswoman said: "Fares for four in 10 journeys will be frozen in Scotland. There will be no rise for off-peak fares in January.
"Peak-time increases will be limited to inflation, one per cent below similar fares south of the Border. This means that, overall, our fare increases will be below inflation."
The Scottish Government said the fares caps would continue into the next ScotRail franchise, which starts next April.
A Government spokeswoman said: "We are committed to ensuring rail fares are affordable across Scotland for all - fare-payers and taxpayers.
"That is why we have capped regulated ScotRail fares increases in the next franchise period at the level of the RPI and off-peak regulated fares increases will be capped at one per cent below RPI."
Five companies have been shortlisted to take over the ScotRail franchise. Current operator First Group is in the running along with Abellio, Arriva, MTR and National Express. The successful bidder will be announced late next month or October.
More than half the revenue from train ticket is split between staff costs and investment in railway infrastructure, with about four per cent covering the cost of electricity or diesel fuel and three per cent per ticket going to train operating companies as profit.
Passenger Focus called on the UK Government to freeze peak fare increases in England at inflation only, as it did in 2014.
David Sidebottom, the director of Passenger Focus, said: "We hope the Government will step in again, as it did last year, to ensure train fares in England do not rise above the rate of inflation."
Chancellor George Osborne will decide before the end of the year.