UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

February 24, 2021

Date of Report (Date of earliest event reported)

PARATEK PHARMACEUTICALS, INC.

(Exact name of Registrant as specified in its charter)

(617) 807-6600

(Registrant’s telephone number, including area code)

Not applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (230.405 of this chapter) or Rule 12b-2of the Securities Exchange Act of 1934 (§ 240 12b-2 of this chapter).

Emerging Growth Company ☐

If an emerging growth company, indicate by a check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

On February 24, 2021, Paratek Pharmaceuticals, Inc., (the “Company”) issued a press release containing an update on its recent business activities as well as those for the quarter and full year ended December 31, 2020. A copy of the press release is furnished as Exhibit 99.1 and is incorporated herein by reference. The Company will host a conference call and live audio webcast on Wednesday, February 24, 2021 at 4:30 p.m. EST to report fourth quarter and year end 2020 financial results and provide a corporate update. As part of this call, the Company will deliver the slide presentation attached to this report as Exhibit 99.2, which is incorporated herein by reference.

The information in this report, including Exhibits 99.1 and 99.2, is being furnished pursuant to Item 7.01 and shall not be deemed filed for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor will it be incorporated by reference in any filing under the Securities Act of 1933, as amended, or in any filing under the Exchange Act, except as expressly set forth by specific reference in such filing.

(d) Exhibits.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.