The 32-year-old, Portugal's record scorer, took his haul in the current qualifying campaign to 14 goals in seven games and his overall tally to 78 in 144 international appearances.
The win left the Portuguese in second place with 18 points from seven games in Group B. Leaders Switzerland are three points clear after beating Andorra 3-0 in a game interrupted by rain. Third-placed Hungary beat Latvia 3-1 to reach 10 points.
The group winners qualify for Russia while the eight best second-placed teams in the nine groups go into a playoff round, with the Swiss having guaranteed at least runners-up spot.
Ronaldo needed three minutes to open his account when he met Bernardo Silva's cross with an acrobatic volley at the far post.
"I've been looking to score a goal like that for a while," he said. "That sort of goal was missing from my career and now I've done it. It was a nice move."
Ronaldo doubled the lead in the 29th, sending Gunnar Nielsen the wrong way with a penalty after Joao Mario was tripped by Roaldur Jakobsen, and nearly completed a hat-trick when his low shot was turned away by the Faroes' goalkeeper.
SANTOS ANGERED
Portugal then eased up and the Faroes, who had already forced an early save from Rui Patricio, pulled one back with the simplest of goals as a long throw-in was headed on at the near post and volleyed home by Rogvi Baldvinsson.
That angered Portugal coach Fernando Santos. "We lost concentration and they scored from a move that we had studied," he said. "I don't like us to concede goals that way, in a loss of concentration."
Midfielder William Carvalho gave Portugal some breathing space by heading in from Ronaldo's cross in the 58th minute.
Carvalho returned the compliment seven minutes later when he slipped the ball to Ronaldo who dummied and fired a left foot shot past Nielsen.
Portugal substitute Nelson Oliveira completed the scoring with an easy goal in the 85th minute after the Faroes defence failed to clear a Ronaldo cross.
Ronaldo's other hat-tricks were against Northern Ireland, Armenia, Sweden and Andorra.
(Writing by Brian Homewood; Editing by Ken Ferris)
