The club posted total revenue of £509million for 2019-20, compared to record revenues of £627.1m in 2018-19, representing a drop of 18.8 per cent.
Revenue had been projected to drop to between £560m and £580m this year because of the club not being involved in the Champions League, but they withdrew the forecast figure when they published their third-quarter results in May because of the impact of the Covid-19 outbreak.
Broadcasting revenues fell sharply from £241.2m to £140.2m, a drop of 41.9 per cent.
United also suffered as a result of the absence of supporters from Old Trafford from March onwards.
Their matchday revenue fell 19 per cent to £89.8m.
Net debt more than doubled from the previous year to £474.1m, which the club said reflected the impact of deferred sponsorship payments of £80m, the loss of advance matchday revenue for 2020-21 which would typically be in excess of £50m ahead of a Champions League season and an increase in player investment.