He made the announcement via social media on Saturday morning, reports CNN.
"Got myself a fiancé just before new year. We are very happy and in love, and our cats are chuffed as well," Sheeran wrote on Instagram.
Last year, Sheeran had revealed he has known Seaborn since they were children but they did not start dating until he invited her to Taylor Swift's Fourth of July party in 2015.
His engagement comes after a roller-coaster year.
His album "÷" ("Divide") -- which also brought him to India -- was the most popular album on streaming services for 2017, according to Nielsen data.
However, his appearance on the popular TV drama "Game of Thrones" was not welcomed by many fans, leading Sheeran to temporarily delete his Twitter account amid the criticism.