Starry S-1IPO registration

Exhibit 23.1

INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM’S CONSENT

We consent to the inclusion in this Registration Statement of FirstMark Horizon Acquisition Corp. (the “Company”) on Form S-1, of our report dated August 25, 2020, which includes an explanatory paragraph as to the Company’s ability to continue as a going concern, with respect to our audit of the financial statements of FirstMark Horizon Acquisition Corp. as of August 18, 2020 and for the period from August 13, 2020 (inception) through August 18, 2020, which report appears in the Prospectus, which is part of this Registration Statement. We also consent to the reference to our Firm under the heading “Experts” in such Prospectus.

/s/ Marcum llp

Marcum llp 

New York, NY 

September 18, 2020