Form S-4 SOUTH PLAINS FINANCIAL,

We have acted as special counsel to South Plains Financial, Inc., a Texas corporation (the “Company”), in connection with the preparation and filing
by the Company on the date hereof of its Registration Statement on Form S-4 (as it may be amended from time to time, the “Registration Statement”) with the Securities and Exchange Commission (the “Commission”) pursuant to the
Securities Act of 1933, as amended (the “Securities Act”), relating to the registration under the Securities Act of up to $50,000,000 aggregate principal amount of the Company’s 4.50% Fixed-to-Floating Rate Subordinated Notes due 2030 (the “Exchange
Notes”).

The Exchange Notes are to be issued under the Indenture (as defined below) pursuant to an exchange offer (the “Exchange Offer”) by the Company in
exchange for a like principal amount of the Company’s issued and outstanding 4.50% Fixed-to-Floating Rate Subordinated Notes due 2030 (the “Original Notes”), as contemplated by the Registration Rights Agreement (as defined below).

This opinion letter is being furnished in accordance with the requirements of Item 21 of Form S-4 and Item 601(b)(5)(i) of Regulation S-K promulgated under
the Securities Act.

In connection with this opinion, we have examined originals or copies, certified or otherwise identified to our satisfaction, of the following:

ATLANTA AUSTIN BANGKOK BEIJING BOSTON BRUSSELS CHARLOTTE DALLAS DUBAI HOUSTON LONDON

LOS ANGELES MIAMI NEW YORK NORFOLK RICHMOND SAN FRANCISCO THE WOODLANDS TYSONS WASHINGTON, DC

South Plains Financial, Inc.

November 12, 2020

Page 2

For purposes of the opinion expressed below, we have relied upon, among other things, our examination of such documents and records of the
Company and certificates of its officers and of public officials as we deemed necessary, including (i) the Company’s Amended and Restated Certificate of Formation, as amended through the date hereof, (ii) the Company’s Amended and Restated Bylaws,
as amended through the date hereof, (iii) the resolutions of the Company’s Board of Directors authorizing registration and the issuance of the Exchange Notes, and (iv) a certificate issued by the Texas Secretary of State on the date hereof to the
effect that the Company is authorized to transact business under the laws of Texas.

For purposes of the opinions expressed below, we have assumed (i) the authenticity of all documents submitted to us as originals, (ii) the
conformity to the originals of all documents submitted as certified, photostatic or electronic copies and the…