Jack Pickett, 19, chose different 26.2-mile routes for each of his marathons, including running 187 laps of the track at his old primary school.
The 19 year-old is an avid runner and member of the Wolverhampton and Bilston AC. He even hopes to be on Team GB one day.
"I am proud of myself and happy that it's over, but I'm still proud that I managed to get them all done," said Jack, after his final run on Sunday following a week of gruelling hard work, which starting on November 9.
"I picked up an injury on Thursday which meant Friday and Saturday's run was pretty difficult," he said. "Mentally, it was getting easier as the week went on but Sunday was tough to get through.
"The charities I had chosen to fundraise for were Cancer Research UK and the Omega charity – my mum, Dawn, works for Omega and another family member is connected to Cancer Research UK.
"I think raising money for charity helped me because it gave me something to go out for each day and helped to motivate me."
Jack managed to complete his first four marathons in three hours 38 minutes. Friday's marathon took just over five hours because of an injury but the weekend went a bit better. Sunday's run came in at three hours 40 minutes.
Jack said: "I finished college last year and have been working in primary schools since on and off, but I took a little break to prepare for this challenge.
"It would be amazing to get into Team GB at some point, whether that's marathons or shorter stuff. My dad ran 20 miles with me yesterday, which was great, and my mum has been there on her bike quite a few days, which helps a lot.
"So far, I've raised around £1,800 with cash donations but I'm still working out the total."
Jack is still accepting last minute donations. Visit www.justgiving.com/crowdfunding/jack-pickett-7in7 to donate.