The singer and actress said that she texts the images in order to keep their marriage "fun".
When asked by radio DJ Billy Bush if she sends Comrie sexy pictures from her phone, Duff replied: "Oh my God you're going to get me in trouble... never with my face in it.
"We've gotta keep it fun, gotta keep it interesting."
Duff said that she trusts Comrie not to send the images to anyone else.
She added: "He'd know better than to forward them on!"