Urruti, 27, has scored 37 goals for Portland and FC Dallas during his six seasons in MLS. He began at Toronto FC, playing two games before being traded to the Timbers. He moved to FC Dallas in the 2015 Re-Entry Draft as the Timbers were faced with salary cap issues.
Urruti had expressed a desire last summer to return to Argentina, where his pregnant wife was living, but a rumored move to San Lorenzo never materialized.
He was a part-time starter at Portland but started 61 games in 2016-17 with FC Dallas.
“Maxi has played a big part in our success at FC Dallas the last few seasons,” said FC Dallas technical director Fernando Clavijo in a team statement. “We’re glad he’ll be a part of the FC Dallas family for the next few years.”