She also uses her craft skills to create new garments from old clothes, for example, she turned a jumper into a jumper vest, she said these sell "really well".
Fiona, from Sheffield, said that she is "addicted" to making money from Depop, and said she likes to spend her cash on travelling with friends.
Sharing a top tip for selling on the site, she said that it is so important to take photos with a great background, such as in a nice spot in the garden.
Speaking to Channel 4's How to Get Rich, she said: "Photography is one of the most important bits of reselling.
"If you don't have good pictures, then people can't see the value of your items".
Fiona, whose Depop stores is called Fifi's Closet, said that she feels so excited and happy when she sells an item "it's a really good feeling", she said.
I’m a top seller on Depop and these are my 7 tips including the right way to sell quickly
She said that in the future she wants to get more vintage sellers on board with her business, and even start her own shop.
Fiona's money making scheme has likely left many people feeling impressed.
Commenting under a YouTube of of the Depop seller, people rushed to share their thoughts.
One person said: "I'm happy for her. she’s working smart."
Top charity shop tips for bagging a bargain
Ross Dutton has been a manager for Crisis's charity shops for four years and currently runs the charity's Finsbury Park shop in London.
Choose your area - As a rule of thumb, the posher the area, the better quality the clothes that are donated.
Don't hang around - If you see something you like, buy it, as it'll likely be gone when you come back
Look out for cut-off labels - Some of your favourite high street stores will have deals with local charity shops to donate stock that isn't sold during their own sales. Often part of the deal is that they need to cut the labels off the clothes.
Stay at home - While some charities have their own site, like and . many also sell from dedicated eBay stores, such as and . You won't get the range of bargains that you would get in a physical store, but if you're looking for something specific it may be worth checking online too.
Another person said: "It's my dream job to selling clothing as full time business."
A third said: "She seems so happy with her job!"
A fourth added: "This is so awesome and inspiring".