The tiny tot was decked out in a rainbow tutu and polka-dot tights for her Alice in Wonderland-themed birthday bash and took the big event in stride—literally.
Hattie's first stroll was captured on home camera for the family to enjoy for years to come.
"Our birthday girl surprised all of us by hitting a huge milestone!" the former 90210 actress said on her blog.
Hattie is seen surrounded by fellow partygoers making her way step-by-step towards her proud mother.
Watch out, Hattie is on the loose!