McFarland, 29, had a career year in 2018. He appeared in 47 games, allowing only 18 runs, holding opponents to a .239 average and compiling a 2.00 ERA -- all career bests. He held left-handed hitters to a .165 average with 22 strikeouts and only two walks. He was second in the National League in ground balls.
McFarland made $850,000 in 2018 and asked for $1.675 million in arbitration. Arizona's offer was $1.275 million.
McFarland spent four seasons with the Baltimore Orioles before joining the D-backs in 2017. He has a career 3.94 ERA, with a 18-14 record, one save and 12 holds.