The Revolutionary Road actress took home the prize for her role in the HBO miniseries Mildred Pierce.
Winslet thanked her mother in her acceptance speech, saying that she will always need the support of her family to be successful.
Winslet's Mildred Pierce co-star Guy Pearce also took home an award for his role in the HBO miniseries, earning the accolade for 'Outstanding Supporting Actor in a Miniseries or a Movie'.
Mildred Pierce centers on a mother struggling to relate to her daughter in the midst of the Great Depression.
More from the Primetime Emmy Awards 2011:
> Downton Abbey dominates miniseries category
> Kyle Chandler wins Emmy for 'Friday Night Lights'
> Peter Dinklage wins Emmy for 'Game of Thrones'
> 'The Daily Show with Jon Stewart' wins Emmy for ninth year in a row
> Ricky Gervais jokes that he is 'not allowed on American soil' in pre-taped segment
> Primetime Emmys host Jane Lynch confronts 'Glee' alter ego Sue Sylvester
> Primetime Emmys 2011: The major winners
Watch Kate Winslet speaking backstage on the Primetime Emmys 'thank you cam' below: