Net migration - the number of people arriving minus those leaving - of 4.9 million people is projected to drive the increase, the ONS said.
The projections are based on an assumption of long-term net migration of 340,000 per year from year ending mid-2028 onwards, it added, cautioning that actual levels of future migration may end up being different.
Net migration to the UK reached a record of more than 900,000 in the year to June 2023.
Between mid-2022 and mid-2032, the ONS projected there will be a similar number of births and deaths in the UK.
"The driver of this growth is migration, with natural change - the difference between births and deaths - projected to be around zero," James Robards, from the ONS, said.
"Our latest projections also highlight an increasingly ageing population, with the number of people aged over 85 projected to nearly double to 3.3 million by 2047. This is in part because of the ageing of the baby boom generation, as well as general increases in life expectancy."
England's population is projected to grow more quickly than other UK nations in the decade to mid-2032, increasing by 7.8 per cent, compared with 5.9 per cent for Wales, 4.4 per cent for Scotland and 2.1 per cent for Northern Ireland.
The ONS also provides a projection further into the future, covering the 25 years between mid-2022 and mid-2047, for which the total projected growth of the UK population is 8.9 million, a jump of 13.2 per cent.
with PA
