Shares of the Minneapolis food giant were falling 3.43% to $59.09 in premarket trading.
General Mills reported net income of $595.7 million, or 96 cents a share, compared with $454.1 million, or 74 cents, last year. Adjusted earnings were 82 cents a share, below analysts' estimates of 84 cents.
Sales totaled $4.52 billion, compared with $4.18 billion last year. Wall Street called for sales of $4.45 billion.
General Mills said the sales boost reflected "broad-based market share gains amid elevated at-home food demand resulting from the COVID-19 pandemic."
Looking ahead, the company said it expects the pandemic to drive continued elevated consumer demand for food at home, relative to pre-pandemic levels, through the remainder of fiscal 2021.
General Mills said it expects fiscal-year net sales to increase about 3.5%. The FactSet consensus calls for full-year sales of $17.83 billion.
The pandemic changed consumer behavior, the company said, with "more time spent working from home and increased consumer appreciation for cooking and baking" and General Mills said it "plans to capitalize on these opportunities."
General Mills said it expects 2021 adjusted operating profit margin to be roughly in line with fiscal 2020 levels.
Separately, General Mills said it had agreed on Tuesday to sell its European Yoplait operations to Sodiaal, a French dairy cooperative, in exchange for full ownership of the Canadian Yoplait business and a reduced royalty rate for use of the Yoplait and Liberté brands in the U.S. and Canada.
The proposed transaction is expected to close by the end of the year.