Portland used targeted allocation money to complete the deal, which includes an option to buy the 23-year-old winger.
Polo joined Morelia in January 2017 and scored two goals in 25 matches (six starts) for the Liga MX club. He also has one goal in 15 caps for Peru since making his debut in 2016, appearing in both legs of the November playoff win over New Zealand that secured the nation's spot at the World Cup.
"Andy is a versatile, young player who will add another element to our attack, and we believe that he has further upside to his development," Timbers coach Giovanni Savarese said in a news release. "Andy has strong technical ability and is able to stretch opponents and run in behind defenses. He will provide us with another quality option as a winger, and we are very pleased to add him to the team this season."
The Timbers have acquired 23-year-old Andy Polo on loan from @FuerzaMonarca for the 2018 @MLS season. Welcome to the Rose City, @AndyPolo94!— Portland Timbers (@TimbersFC) January 17, 2018
DETAILS | https://t.co/qzkt6HTl5p #RCTID pic.twitter.com/QPtZborfVu
The 5-foot-9 attacker began his career with Peruvian clubs Universitario and Universidad San Martin before joining Inter in January 2014. Polo never made an appearance for the Serie A giants, however, signing with Colombian side Millonarios in July 2014.
Polo is poised to help fill the void in Portland left by the December departure of Darlington Nagbe to Atlanta United.
"We are excited to add a young and talented attacking player in Andy Polo," Timbers general manager Gavin Wilkinson said. "He has already proved himself at a young age in various leagues and at the international level, and we look forward to welcoming Andy and his family to Portland and MLS."