Carrizo Oil & Gas (CRZO) 10-K 2017 FY Annual report

Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

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

(1) Registration Statements (Form S-3 Nos. 333-221121, and 333-221122) of Carrizo Oil & Gas, Inc. and in the related Prospectuses,

(2) Registration Statement (Form S-8 No. 333-218036) pertaining to the 2017 Incentive Plan of Carrizo Oil & Gas, Inc., and

(3) Registration Statements (Form S-8 Nos. 333-196252, 333-181585, 333-162888, 333-137273, 333-116528, 333-55838, and 333-35245) pertaining to the Incentive Plan of Carrizo Oil & Gas, Inc.,

of our reports dated February 28, 2018, with respect to the consolidated financial statements of Carrizo Oil & Gas, Inc. and the effectiveness of internal control over financial reporting of Carrizo Oil & Gas, Inc. included in this Annual Report (Form 10-K) of Carrizo Oil & Gas, Inc. for the year ended December 31, 2017.

/s/ Ernst & Young LLP

Houston, Texas

February 28, 2018