One good idea for invitations to an ugly sweater party is making sweater-shaped invitations with foldable sleeves and using a button with string to close them up. Hosts can also take or reuse a photo of themselves wearing ugly sweaters and turn it into an invitation.
Use funny wording to catch the recipient's attention. Embellish the invitation with buttons, relevantly themed stickers and sweater material. To really establish the theme, use common ugly sweater patterns or designs as borders and backgrounds. Ugly sweater party invitations must clearly state that everyone has to wear an ugly sweater to be granted entrance.