Championship, defeating South Africa's Keegan De Lange 4&3 in the 36-hole Final at Royal Birkdale.
The 17-year-old is the second Swedish player in succession to win the Boys Amateur, after Oskar Bergqvist's victory at Prestwick last year. Svensson, from Halmstad Golf Club, recovered from a stomach illness earlier in the week that almost forced him to withdraw in the qualifying stroke play rounds to earn the biggest victory of his young golfing career.
"It's almost unbelievable, it means so much to me and I couldn't be more happy," said Svensson after lifting the trophy. "You put so many hours and so much hard work into this game and finally it pays off.
"After the first qualifying round I was very ill in the night and the morning of the second day I almost couldn't bring myself to the golf course as I was very weak. So to be standing here at the end and winning is not what I thought would happen.
"I am very good friends with Oskar (Bergqvist) so it is great to defend the title that he won for Sweden. I guess the secret is to be Swedish and play good golf," he laughed.
The competitors enjoyed benign conditions on the historic Merseyside links on Sunday, with Svensson taking full advantage of scoring opportunities to play the morning session in four-under-par.
De Lange, from Pretoria Country Club, opened with a double-bogey 6 and dropped another shot on the 3rd hole to give Svensson the early lead, which he didn't relinquish for the rest of the match.
After a slow start, the left-handed South African looked to be getting back into the match as the pair approached the turn, carding birdies on the 6th and 8th holes, but his momentum was checked as Svensson delivered a birdie of his own on the 8th and rolled in his putt on the 10th for a birdie three to go back to two-up.
Svensson pushed on from there, taking a five hole lead as De Lange struggled down the back nine until the Swede dropped his only shot of the morning on the 14th. De Lange sought to capitalise on this mistake and he holed a 30-foot eagle putt on the 15th to cut Svensson's advantage to three holes but the Swede bounced back with a birdie on the 17th which gave him a four hole lead going into the afternoon.
The afternoon session saw Svensson struggle to maintain his momentum as he carded four bogeys against a single birdie on the front nine and De Lange reduced the deficit to two holes by the turn.
After a bogey on the 28th hole left De Lange three holes behind, he matched Svensson's birdie on the next before a duffed approach shot into a pot bunker on the 31st hole resulted in a double bogey six and left his opponent four up with six to play.
De Lange managed to stay alive after getting up-and-down from the edge of a greenside bunker on the 32nd to halve the hole but Svensson matched his par five at the 33rd hole to secure a 4&3 win.
"It was a bit of a struggle out there today and I wasn't playing my best golf but I had an unbelievable week so I can't be angry about that. Marcus played really well and put the pressure on early in the game and kept it going. All in all, well played to Marcus, he deserved the win," said De Lange.
"This was unbelievable, playing Royal Birkdale. In the practice round I was wondering how to break 80. I'm very pleased with myself and I achieved what I thought was impossible so I am very happy. I hope to be back here to play one day in The Open or The Amateur, that would be the dream."
With the victory, Svensson earns a place in the 2016 Amateur Championship which will be held at Royal Porthcawl and Pyle & Kenfig.