Finley is best known for his long career with the Angels, during which he won more than 15 games six times. His finest season was in 1990, when he won 18 games to just 9 losses and posted a 2.40 ERA. After departing the Angels, Finley signed with the Indians before the 2000 season. He went 16–11 with a 4.17 ERA and posted an 8–7 record with a 5.54 era with the Indians in 2001. In 2002 he was 4–11 with a 4.44 ERA in 18 games before being traded to the Cardinals for outfielder Coco Crisp. He finished the season and subsequently his career with the Cardinals, going 7–4 with a 3.80 ERA for the remainder of the season,

Finley is the only pitcher in the history of Major League Baseball to record 4 strikeouts in a single inning more than once; he accomplished the feat 3 times. These occasions were on May 12, 1999, then later again that season on August 15, both with the Anaheim Angels, and then for a third time on April 16, 2000, with the Cleveland Indians. This oddity can mainly be attributed to the fact that he used an excellent split finger pitch as his strike out weapon; that pitch would often end up in the dirt, eluding both batter and catcher.

Finley was selected by the Angels in the 15th round of the 1984 amateur draft out of Northeast Louisiana University, but he did not sign. The Angels chose him again in the 1st round (4th pick) of the secondary phase of the 1985 amateur draft.

Finley became eligible for the National Baseball Hall of Fame in 2008. 75% of the vote was necessary for induction, and 5% was necessary to stay on the BBWAA ballot. He received 0.2% of the vote and dropped off of the ballot.

On April 9, 2009, Finley was to be inducted into the Angels' Hall of Fame along with former teammate Brian Downing before the start of the game that day. However, due to the death of Angels rookie pitcher Nick Adenhart, the ceremony and game was postponed until August 27, 2009.

On July 11, 2010, Finley was the winning pitcher in the 2010 Legends & Celebrity Softball Game at Angel Stadium.

Finley, similarly to Randy Johnson, was a rare left-handed power pitcher and often finished in the top 5 in the league in strikeouts. He complemented his hard fastball with a devastating forkball that would baffle hitters when on target. The best comparison to Finley for pitching style would be right-handed Roger Clemens, though Finley had less consistent command of his pitches than Clemens.

Finley was married to actress Tawny Kitaen from 1997 to 2002. He filed for divorce three days after Kitaen was charged with committing domestic violence against him, having beaten him with a stiletto heel. They have two daughters, Wynter and Raine. Tawny Finley, in a declaration to the Orange County Superior Court, claims her husband, Chuck Finley, used steroids amongst other drugs. She even details that Finley bought the steroids from a man named "Rob" from Mission Viejo, and that she has seen him inject himself. She also claims he bragged about being able to circumvent MLB's testing policy. He currently lives in Yorba Linda, California with his family.

As Finley took the mound for an April 2002 game against the Chicago White Sox at then-Comiskey Park II, the stadium's musical director, Joe Stephen, took a subtle dig at Finley's messy divorce, and played "Here I Go Again" by the band Whitesnake, referencing Kitaen's appearance in that band's videos. Stephen was later fired and the White Sox apologized.