Eskilstuna District Court on Friday sentenced Nicklas Bäckström to four years and six months in jail.
The search for both the culprits and the jewels gained international attention after the crowns were taken from a cathedral in Strängnäs, one hour from Stockholm, with the suspects then seen fleeing the scene by bicycle and motorboat.
The crowns and orb were thought to be gone forever, when a security guard in Åkersberga, north of Stockholm, found them in a rubbish bin marked “bomb” earlier this month.
Bäckström's DNA was found on two of the items, and then confessed to having carried out the theft. He was already on trial after being identified by blood found at the crime scene, but during the initial police investigation had denied any involvement in the heist, admitting only to having supplied the getaway vehicles.
Another two men, aged 26 and 24, are currently in custody on suspicion of handling stolen goods in connection with the recovery of the royal jewels. According to police they are friends of the 22-year-old.
The crowns were made for the burial of King Charles IX and his wife Christina and date back to the early 1600s. They were stolen along with a royal orb. Some of the items were partly damaged in the theft, but experts believe it may be possible to restore them close to their original condition.