In the early years of her career in the 1960s, Wiggen took a particular interest in electronics. She then began painting portraits, followed by precise depictions of human internal organs. In the 2010s, Wiggen achieved international breakthrough and wider recognition with her Iris paintings.
Ulla Wiggen approaches her subjects with calm realism, often using a subdued colour palette. Her works are precise and deliberately detached depictions of their subjects. However, their themes and details provoke contemplation about human existence, the body, and the mind.