[1] At the age of 16, Søndergaard was rewarded with a youth contract in Viborg and shortly after, began training with the first team.
On 24 June 2020, Søndergaard got his official debut for Viborg in a Danish 1st Division game against Skive IK.
As of the beginning of the 2020-21 season, Søndergaard became a permanent part of the first team squad at Viborg and on 17 September 2020, Søndergaard signed a new deal with the club until June 2023, which would see him go on full-time from the summer 2021.
At the start of the 2024-25 season, Søndergaard was injured and was out for two months until September 2024, when he made his comeback in a match against Sønderjyske.
[7] In January 2025, Søndergaard suffered a fracture in his foot, which forced him to sit out the coming period.