Exhibit 13.1

CERTIFICATION PURSUANT TO 18 U.S.C SECTION 1350, AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with this annual report on Form 20-F of Oatly Group AB (the “Company”) for the fiscal year ended December 31, 2023 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Jean-Christophe Flatin, Chief Executive Officer of the Company and Principal Executive Officer of the Company, hereby certify pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to my knowledge:

i.The Report fully complies with the requirements of Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934, as amended; and

ii.The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: March 22, 2024

By:	/s/ Jean-Christophe Flatin
	Jean-Christophe Flatin
	Chief Executive Officer
	(Principal Executive Officer)