Tanak's comfortable win was the second in a row in the South American country for the 2019 world champion, albeit after a three-year absence, and his second of the season after Sweden in February.
The Estonian won Rally Chile with Toyota in 2019 when the event made its championship debut and he took seven of the 16 gravel stages this time, using clever tyre strategy to build a solid overnight lead.
Belgian Thierry Neuville (35) finished second for Hyundai, 42.1 seconds behind, after teammate Teemu Suninen (29) hit a tree stump and retired in Sunday's penultimate stage.
Elfyn Evans (34) was third for Toyota, with championship-leading teammate Kalle Rovanpera fourth.
Suninen's exit and the lost points meant Toyota clinched the title for the seventh time but Rovanpera, who celebrated his 23rd birthday on Sunday, will have to wait for his second crown.
The Finn, who won three stages, now leads Evans by 31 points.
The new Central European Rally on asphalt roads in Austria, Germany and Czech Republic is next on October 27th-29th.
