Mahmudur Rohman, 46, and Kamal Rahman, 54, both from Peterborough, were convicted at Leicester Crown Court.
They supplied 116 tonnes of vacuum packed boneless turkey thigh pieces described as boneless halal lamb leg to butchers and restaurants.
Investigations began after Leicester City Council’s Food Safety team increased testing in 2013 after the horsemeat scandal.
The fraud was uncovered by Trading Standards following sampling by Environmental Health Officers.
They found meat being supplied as lamb to shops and restaurants in the East Midlands, Middlesbrough and Portsmouth was turkey.
Trading standards traced the "lamb" to now defunct Dutch Bangla Direct, whose director was Rohman.
It was estimated that Dutch Bangla Direct made a profit of between £300,000 and £400,000 between January 2013 and October 2014.
Judge Tregilgas-Davey said the fraud was ‘motivated by greed and financial gain’.
“The number of people affected by the fraud was high: it includes the 50 or so outlets that Dutch Bangla Direct sold to, but also all the customers who bought from those shops and restaurants.
“Perhaps the most aggravating factor in the case is that non-Halal meat was sold on as Halal meat. I take on board that the meat supplied had been slaughtered in a Halal compliant manner, but it was not certified.
“I witnessed during trial how distressing it was to individuals that they themselves and their families had consumed this non-Halal meat, and how distressing it was that they supplied on to their customers.”