The Baltimore company reported net income of $184.5 million, or an adjusted 12 cents a share, against a loss of $15.3 million, or an adjusted 3 cents, in the year-earlier quarter. Revenue fell to $1.4 billion from $1.44 billion.
Analysts were expecting a loss of 6 cents a share on revenue of $1.27 billion.
"Improving brand strength and consistent operational execution delivered better than expected results in the fourth quarter," Chief Executive Patrik Frisk said in a statement.
"As we continue to navigate uncertainty around the pandemic, we remain focused on execution and the efforts necessary to stabilize our business further."
Under Armour shares at last check were up 6.2% to $22.
Under Armour earlier had said it would implement a $550 million to $600 million restructuring plan for 2020 designed to rebalance its cost base and improve profitability.
The company reported $473 million of pretax charges for the year and expects to recognize additional charges related to this plan in the first half of 2021.
For the year, Under Armour's revenue was down 15% to $4.5 billion. Its gross margin widened 1.4 percentage points to 48.3% due to channel mix and supply-chain initiatives, offset by pricing discounts in its direct-to-consumer channel
Expenses decreased 3% to $2.2 billion, or 48.5% of revenue, in 2020.
For 2021, Under Armour expects revenue to be up in the high-single-digit-percent rate with gross margin improving to 48.6%. The company expects adjusted earnings of 12 cents to 14 cents per share.
FactSet's consensus earnings estimate is for 17 cents a share for 2021.