A Victorian woman may face serious criminal charges after police spotted her riding a bike with a toddler tucked under her arm.

Police were patrolling in Wangaratta, in north-eastern Victoria, when they came across the 19-year-old riding an electric-powered bicycle along College Street late Friday afternoon.

The woman was steering with one hand while carrying the 16-month-old boy under her other arm.

Neither was wearing a helmet.

Police said they were dumbfounded by the reckless riding and said the woman refused to acknowledge her actions posed any danger to her nephew.

She was arrested and may be charged with conduct endangering life.