Justin Sidhu, from Edmonton in western Canada, was convicted yesterday after a two-day trial.
During the trial, the Crown argued that Sidhu carried an envelope into the remand centre on September 19, 2013, and handed it to his client in an unmonitored interview room.
Guards later opened the envelope and found some sheets of paper, one photograph, cigarette rolling papers, a birthday card and a Christmas card, and six grams of methamphetamine.
"The real issue here is Mr Sidhu's knowledge," he said.
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Little said the only reasonable inference he could draw was that Sidhu knew the envelope contained drugs.
"I find you guilty of the offence charged, and wish to say I find no satisfaction in that decision," he said.
Sidhu, however, remains free on bail, reported Canadian Broadcasting Corporation.
Earlier, Prosecutor Anita Chan told the court Sidhu knew exactly what was in the envelope, and lied so he could bring the drugs to Clarke.
The fact that Sudhu told the guard the envelope contained documents and a picture was significant, she said, because it showed he knew what was inside.
The prosecutor noted that drugs are extremely valuable in jail, worth five to 10 times what they are on the street. The six grams of meth would have been worth about 6,000 dollars, she said.
No conclusive fingerprints were found on any items in the envelopes.
Clarke recently pleaded guilty to drug possession charges in connection with the case. He was given a 45-month prison term.