Figures for February into March show the annual average performance figure rose to 90.3%.
This, however, remains below the benchmark set in the rail franchise contract. This committed ScotRail to a performance target of 91.3%.
But the improvement does end the need for a performance improvement plan to remain in force.
This mechanism was put in place in September 2016 when the Scottish government demanded improved punctuality and reliability.
ScotRail outperformed other parts of the UK in the latest round of figures, with the annual average for England and Wales slipping slightly to 87.3%.
In November, a major improvement plan was published in response to widespread criticism of ScotRail's reliability since Abellio took over the contract in April 2015.
It aims to improve punctuality and reliability through measures such as infrastructure developments and "performance workshops" for managers and staff.
ScotRail Alliance Operations Director Perry Ramsey said: "We will continue to focus on delivering the best service to our customers, seeking to make improvements every single day. This is what our customers want and is our number one priority.
"We have had a challenging year. We have been working to deliver one of the biggest upgrades to the rail network since it was built in Victorian times - while still running a full service.
"That work was necessary so that we could introduce new faster, longer, greener trains - giving people more seats and shorter journeys."
Transport minister Humza Yousaf, who ordered the improvement plan, said: "These figures also show the improved performance widens the gap between rail performance in Scotland and the rest of the UK.
"It is equally important to recognise the real efforts made by ScotRail staff who are working hard round the clock, in all weathers, to lift performance and deliver rail services which passengers both desire and deserve.
"I remain focussed on ensuring Transport Scotland and ScotRail work with the industry to maintain this upward trend and that the PIP initiatives remain in place to deliver even more improvement over the next few months."
The reliability of ScotRail services has improved for the fifth monthly period in a row, new figures show.