Riddell had been rushed to hospital in Aberdeen on Sunday night for emergency surgery, but his condition deteriorated over the following days and he slipped away, flanked by his wife Rebekah and close friends and family.
The couple received the news while on honeymoon that Riddell had been diagnosed with a stage four glioblastoma – a form of brain tumour – and he had been undergoing chemotherapy and radiotherapy in Aberdeen. He underwent a biopsy two weeks before his wedding in July.
Nairn's midweek game against Rothes was pulled on Tuesday morning as news of Riddell's condition filtered to close friends, some of whom play for Rothes.
Saturday's home game against Huntly is postponed and there will be a minute's silence as a mark of respect before all other Highland League matches this weekend.
A benefit game for Riddell planned for this Sunday at Station Park will go ahead.
Nairn County confirmed the player's death last night.
The statement said: "With the permission of his family, Nairn County Football Club is saddened to confirm that our player, Calum Riddell, has passed away very peacefully surrounded by family and friends. He was 28.
"Calum was diagnosed with stage 4 Glioblastoma – a malignant brain tumour – in the summer and died at Aberdeen Royal Infirmary on Tuesday afternoon.
"Calum came through the club’s youth development programme as a youngster before moving on to Nairn St Ninian, where he spent eight successful seasons, playing a huge part in the Elginshire Cup-winning team of 2012.
"He returned to his boyhood club in the summer of 2016 for another crack at the Highland League and made 28 appearances before the early symptoms of the disease that was to go on to claim his life rendered him unavailable for selection towards the end of last season.
"The match at Rothes tonight had already been postponed given Calum’s condition and Saturday’s home match against Huntly will be postponed too. The club would like to thank Rothes FC, Huntly FC and the Scottish Highland Football League for their understanding at this difficult time.
"Sunday’s benefit match for the Calum Riddell Fund between Nairn County FC and the Calum Riddell All Stars will still go ahead at the request of Calum’s wife and family.
"Everyone at the club extends their sincere condolences to Calum’s family and friends and asks that their privacy be respected at this time."
*** To donate to the gofundme page, click here: https://www.gofundme.com/calumriddellfund