Mills was due to return to Perth Scorchers having made seven appearances in their title-winning campaign last season but has been forced to pull out.
A club statement read: "Perth Scorchers fast bowler Tymal Mills will not be available for the 2022/23 KFC Big Bash League season due to a family emergency.
"Mills was recruited by Perth in the inaugural BBL12 Draft after playing an important role during the Scorchers' title-winning BBL11 campaign. The club fully supports Mills' decision, and sends its thoughts and best wishes to his family during this time."