"It was just in a pocket ... in the parka," said Sgt. Del Byron of the RCMP in God's Lake Narrows. "Wrapped in tape, a small package."
Police say the 39-year-old woman was arrested Friday as part of an ongoing investigation.
She and the 15-month-old girl had just arrived at the community airport from Winnipeg.
Byron wouldn't say what led officers to search the child, but added: "If we have information, we act on it."
The little girl was fine and remained calm the whole time, he said.
The woman faces a charge of possession of a controlled substance for the purpose of trafficking.
Police continue to investigate.
Cpl. Miles Hiebert, an RCMP spokesman in Winnipeg, said officers don't often encounter cases where children are used to smuggle drugs.
"It is unusual," he said. "I'm not saying that we're running into it all the time, but ... people are willing to take chances even with their own grandchildren and use them for their own purposes."
Hiebert said police are constantly working to stem the flow of illicit drugs into northern communities.
"The methods are limited only by the creativity and imagination of the people smuggling them, so we have to be contantly aware and monitoring."