Donaldson, 29, had sought $5.75 million. Arbitrators Steven Wolf, Robert Herzog and Gary Kendellen heard his case.
Donaldson, who hit .255 in 158 games last season for Oakland, was traded to Toronto in December for third baseman Brett Lawrie, left-hander Sean Nolin, right-hander Kendall Graveman and minor league shortstop Franklin Barreto.
In four seasons in the majors with the A's, Donaldson has a .268 average with 63 homers and 228 RBIs.
He earned the $500,000 minimum last year and was eligible for arbitration for the first time.
Teams lead players 5-3, with the remaining seven cases scheduled for next week. The eight hearings are the most since clubs went 5-3 in 2010. There have not been more since teams were 8-6 in 2001.
In other arbitration cases:
The Miami MarlinsbeatDavid Phelps in salary arbitration, as the pitcher was awarded $1.4 million. He had requested $1.875 million. He was 5-5 with a 3.82 ERA in 17 starts and 15 relief appearances for the New York Yankees last year, when he made $541,425.
The 28-year-old right-hander was traded to Miami in December along with versatile Martin Prado for right-hander Nathan Eovaldi, outfielder Garrett Jones and a minor leaguer.
The Associated Press contributed to this report.
Josh Donaldson To Earn $4.3M
Jerry Crasnick discusses why Blue Jays third baseman Josh Donaldson was awarded $4.3 million in arbitration instead of the $5.75 million he had been seeking.