Multiple upload images in active_admin with Active Storage

You just need do some changes

model:

has_many_attached :images

instead of

has_one_attached :image

activeadmin:

permit_params images: []

form do |f|
  f.inputs do
    f.input :images, as: :file, input_html: { multiple: true }
  end
end

and you'll can choose many files to upload