Krisnnapillai Saseendran, who runs a Spar and a Costcutter in Margate, was convicted of 21 offences under the Food Safety Act. Following a tip-off, Kent Trading Standards officers found several out-of-date items on display in the two stores.
Krisnnapillai was fined £150 per instance, plus £300 costs. He had previously been cautioned by Kent Trading Standards for the same offence, which had "repeatedly" occurred over at least two years.
The Use By date indicates a date after which food may become unsafe to eat. This is different to a Best Before date, which indicates to consumers that food may go stale but is unlikely to be harmful.
Kent Trading Standards area manager Mark Rolfe said: "Food that is past its Use By date can become unsafe to eat, and to knowingly sell that food to members of the public is irresponsible and illegal.
"Food safety is a serious matter and this prosecution should send out a clear message to retailers that we will act on those ignoring the law."