The more than 300 year old estate, which owns 90 acres of London property, saw the value of the real estate portfolio fall 14.2%, or by around £795 million, to £4.8 billion in 2020.
That was led by declines in its retail arm, down 24.6%, with shops having to close at various points due to lockdowns.
The landlord saw rental income hit after offering support to a number of tenants during the period, including switching a number of hospitality firms to turnover-based rents.
Other assistance such as rent holidays, deferrals and discounts were offered in some cases.
Chief executive Hugh Seaborn cheered some recent encouraging signs, such as an uptick in retailer enquiries to open new shops.
Since the latest lockdown started to ease in April, footfall has reached as high as 90% of pre-Covid levels, and restaurants have “been overwhelmed with business”. Seaborn added that office occupancy across the estate hit around 50% at one point.
Cadogan also completed significant new lettings in 2020, welcoming fashion brands including Ganni.
Seaborn said: “From the outset of the pandemic, Cadogan has been proactive, with clear priorities for dealing with the crisis and plotting a path for emerging successfully as the threat to health recedes and restrictions start to lift.”
Looking ahead, Cadogan has a target of becoming net-zero by 2030, using measures such as having more trees and plants in upcoming projects.
Dividends paid to Earl Cadogan’s family and charitable trust, who are behind the estate, dropped to £17.4 million from £41.4 million.