Figures for the first quarter of the 2021/22 financial year show a rise of £16.6 million in "employee benefit expenses" compared with the corresponding period of the previous year.
The total amount spent on salaries during the quarter ended September 30, when the club re-signed Ronaldo and also brought in Raphael Varane and Jadon Sancho, was £88.5 million.
This rise was offset by £17.4 million brought in through player sales, principally Dan James' move to Leeds, although the club did also earn a sell-on fee from Romelu Lukaku's transfer from Inter Milan to Chelsea.
Total revenue increased by 16.1 per cent to £126.5 million, explained largely by the increase in matchday income after fans returned following the lifting of coronavirus restrictions.
Commercial revenues rose by 7.9 per cent to £64.4 million. This will partially have been driven by the arrival of Ronaldo, although the Portuguese star was only back at the club for the final month of the quarter.
The club, without silverware since 2017, slipped to sixth in the Premier League after recent losses to rivals Liverpool and Manchester City.
Manager Ole Gunnar Solskjaer is under increasing pressure, with the club currently nine points behind leaders Chelsea despite their high-profile signings.
United's executive vice-chairman Ed Woodward said: "While these financial results today demonstrate our resilience through the pandemic, our top priority is success on the pitch.
"The manager, players and everyone at the club are determined to achieve that objective."