The 58-year-old producer and photographer's rep revealed to People this week that Joe is recovering after being diagnosed with prostate cancer in September.
Joe had prostate surgery after his diagnosis that doctors said went well. He is eating healthier and back at work, where is slated to shoot the cover of Nation-Alist magazine and several other campaigns.
"He's feeling great now and is optimistic," a source told People. "He's felt so much love and support from his family and friends."
Joe shares daughters Jessica and Ashlee Simpson with ex-wife Tina Simpson. The 36-year-old designer and 32-year-old singer supported their dad at his first-ever photography exhibit in Los Angeles in May.
"[Jessica and Ashlee are] so professional. They're so good and they know how to work a camera," Joe told E! News at the event. "They know their stuff."
"Their joy makes me happy," he added. "As a father, it's not what your children do. It's who your children are and are they happy? That's the question you'll always ask."
Joe has produced several of his daughters' projects, including Newlyweds: Nick & Jessica and The Ashlee Simpson Show. He also executive produced episodes of ABC series Women's Murder Club.