In the show, a millionaire goes undercover, volunteering at different non-profits and, many times, surprising the charities with a donation.
This week, the Casey Cares Foundation, with a local office in Downingtown, will be featured.
The charity helps the families of children who are critically ill.
Cullen Jones, 9, and his family are among those they've helped. Less than two years ago, he was in the hospital battling stage four Hodgkin's lymphoma, a cancer that starts in the lymph system.
"I was just numb, really. I was just absolutely numb," said his mother, Christine.
His mother said it was a very difficult year for the entire family, but the Casey Cares Foundation made things a little easier.
"We help not only the critically ill child but the entire family," said founder Casey Baynes.
For some, it's as simple as a pajama party while others get up close to their favorite sports team.
For the Jones' they went to Hershey Park, the circus and saw Disney on Ice.
"We saw Princesses on Ice and Nemo," said Lila and Evan Jones, Cullen's brother and sister.
"It took the focus off Cullen being sick and it really boosted us into doing family things again," said Christine.
Cullen said he enjoyed all of the activities, saying "I was stuck doing nothing in the hospital."
As for "Secret Millionaire," Casey didn't want to give anything away, but said "It's one of those things where you see those types of shows and you think, 'Really, guys, you didn't see this coming?' We just thought she was another volunteer interested in our mission."
You can tune in to see what happens on Secret Millionaire this Sunday, August 4th, at 8:00 p.m. on 6abc.
For more information about the Casey Cares Foundation, visit their website at CaseyCaresFoundation.org.