A total of 86.7 per cent of services arrived within five minutes of schedule in the four weeks to 4 January.
That was 2.5 percentage points better than the previous year and 3.4 points up on 2017 – the standard comparison because of weather.
ScotRail also improved its key punctuality measure to the best since June 2018.
The “moving annual average” – performance over the last year – was up 0.2 points to 88.5 compared to a month ago.
But it remains 4 points short of the 92.5 per cent target.
The Abellio-run franchise will end three years early in 2022 due to a funding dispute. Alex Hynes, managing director of Scotland’s Railway, which also includes Network Rail said: “It is fantastic to see such an encouraging period of performance during a challenging time of year.
“We look forward to delivering an increasingly reliable service.”