The 36-year-old previously spent three seasons with the Spitfires before joining Sutton in May 2015.
He scored 11 goals for the club and has also previously played for Woking, Crawley Town and Newport County.
McAllister will go straight into the Eastleigh squad for their National League home match against Tranmere Rovers on Saturday.
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Striker Craig McAllister has rejoined National League club Eastleigh from Sutton United.