Hall, 28, was designated for assignment by Arizona earlier in the week to create room on the 40-man roster for Michael Bourn. He appeared in 12 games at Triple-A Reno to begin the season, posting a 7.98 ERA in 14.2 innings.
Hall, who was the Giants' 19th-round pick in the 2011 draft, made his major-league debut for San Francisco last year. He posted a 6.48 ERA in 8.1 innings out of the Giants' bullpen.
Hall will join the Marlins' Triple-A affiliate in New Orleans, providing a depth arm for the major-league club. He will take a spot on the team's 40-man roster.
Hall is the owner of a lifetime 13-11 record and 2.91 ERA in six minor-league seasons with the Giants' and Diamondbacks' organizations.