EXHIBIT 22.1

List of Subsidiary Issuers of Guaranteed Securities

As of June 30, 2021, Corporate Office Properties Trust was the guarantor of the outstanding guaranteed debt securities of its subsidiaries, as listed below:

Debt Instrument Issuer
5.000% Senior Notes due 2025Corporate Office Properties, L.P.
2.250% Senior Notes due 2026Corporate Office Properties, L.P.
2.750% Senior Notes due 2031Corporate Office Properties, L.P.