Andrea Giesbrecht had been charged with six counts of concealing the body of a child. Each charge carries a sentence of up to two years in jail.
Manitoba provincial court Judge Murray Thompson read out his decision on Monday after a months-long trial.
The remains of the infants were found in the locker in October 2014.
Judge Thompson said the evidence presented at trial left "no doubt" that Ms Giesbrecht concealed her pregnancies and the resulting delivery of the six infants.
