Mama June scored a legal victory in her custody battle over Anna “Chickadee” Cardwell‘s oldest daughter … she’s been awarded temporary custody of Kaitlyn.

The reality TV star is duking it out in court with Michael Cardwell for custody of 11-year-old Kaitlyn, and a judge just ruled she should be with her grandmother, at least until a future court hearing on the matter … according to new legal docs.

Michael — who did have a daughter, Kylee, with Anna — is not Kaitlyn’s biological father.

In the docs, obtained by TMZ, Mama June says Kaitlyn does not have a legal father, and her biological father is unknown.

Mama says she’s been caring for Kaitlyn since Anna’s death, and says Kaitlyn moved in with her a month before Anna died from cancer.

As we reported … Michael filed legal docs last month seeking custody of Kaitlyn, claiming he’s taken a parental role in her life over the years despite not being her biological dad.

While there’s no battle over 8-year-old Kylee — she’s living with her father — June’s vowed to continue fighting Michael for custody of Kaitlyn … and so far she’s winning.

Radar Online was first to report the news.