Montero became the sixth summer signing when he joined the Swans in July 2014 from Mexican club Morelia for an undisclosed fee.
The Ecuadorian international, renowned for his pace, followed Lukasz Fabianski, Gylfi Sigurdsson, Bafetimbi Gomis and Stephen Kingsley to the Liberty after signing a four-year deal.
He impressed in his debut season at the Liberty, making 22 starts for the Swans in the club’s record-breaking league campaign scoring once with seven assists.
At the end of the campaign he featured in Ecuador's Copa America campaign, which saw them exit at the group stage.
He made 24 appearances - scoring once - in 2015-16 as the Swans finished 12th in the Premier League.
He also helped Ecuador reach the Copa America quarter-finals in June 2016.