Not all members of the kingdom Fungi are multicellular. While many fungi are multicellular, forming complex structures like mushrooms and molds, there are also unicellular fungi, known as yeasts.

Yeasts are single-celled organisms that belong to the kingdom Fungi. They are microscopic and reproduce by budding, where a new cell grows from the parent cell.

So, the answer is no, not all members of the kingdom Fungi are multicellular.