Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the following Registration Statements:           

1. Registration Statement (Form S-3 No. 333-239780) of Marinus Pharmaceuticals, Inc.;

2. Registration Statement (Form S-3 No. 333-237903) of Marinus Pharmaceuticals, Inc.;

3. Registration Statement (Form S-8 No. 333-258677) pertaining to the Marinus Pharmaceuticals, Inc. 2014 Equity Incentive Plan, as amended, and Individual Nonqualified Stock Option Awards;

4. Registration Statement (Form S-8 No. 333-239785) pertaining to the Marinus Pharmaceuticals, Inc. 2014 Equity Incentive Plan, as amended, and Individual Nonqualified Stock Option Awards;

5. Registration Statement (Form S-8 No. 333-233131) pertaining to the Marinus Pharmaceuticals, Inc. 2014 Equity Incentive Plan, as amended, and Individual Nonqualified Stock Option Awards;

6. Registration Statement (Form S-8 No. 333-219613) pertaining to the Marinus Pharmaceuticals, Inc. 2014 Equity Incentive Plan; and

7. Registration Statement (Form S-8 No. 333-200701) pertaining to the Marinus Pharmaceuticals, Inc. 2014 Equity Incentive Plan;

of our report dated March 24, 2022, with respect to the financial statements of Marinus Pharmaceuticals, Inc. included in this Annual Report (Form 10-K) of Marinus Pharmaceuticals, Inc. for the year ended December 31, 2021.

/s/ Ernst & Young LLP

Philadelphia, PA

March 24, 2022