The stock was falling 16% to $9.25 a share in after-hours trading, after having fallen 3.9% in the regular session.
For the fourth quarter ended Aug. 3, UNFI earned 36 cents a share on a GAAP basis, compared with 64 cents in the year-earlier quarter.
The latest adjusted earnings per share came in at 44 cents, missing the FactSet-compiled Wall Street estimate of 47 cents.
Net sales were $6.41 billion, in line with analysts' expectations.
The Providence, R.I., company's supermarkets segment saw sales grow by more than a factor of five in the quarter versus a year earlier.
"This past fiscal year has been a transformational one for us as we began realizing some of the key benefits and competitive advantages from the Supervalu acquisition that will be the foundation of our long-term success," said Steven Spinner, chairman and CEO.
The company guided for full-year 2020 sales of $23.5 billion to $24.3 billion, compared with the forecast of $24.35 billion.
Management is looking for adjusted EPS for 2020 of between $1.22 and $1.76 against analysts' forecast of $1.32.
The stock was up 1.4% for the year coming into the earnings report.