The TV star, 39, wed his agent Ali at St Michael's Church in his native Newcastle.
His TV husband Ant McPartlin was best man - naturally! - and Dec's older brother Father Dermott Donnelly conducted the service.
Ant and Dec arrived in Aston Martins, while Ali arrived at the church in a classic silver Rolls Royce.
The bride looked stunning in a Phillipa Lepley ivory silk gown with veil. Groom and best man wore matching blue Tom Baker suits with grey waistcoats.
After exchanging vows in front of a star-studded congregation - dubbed the Geordie Royal wedding - the couple stepped out of the picturesque church and shared a kiss for the cheering crowds.
Holly Willoughby, Dermot O'Leary and Fearne Cotton attended the wedding - with Fearne looking heavily pregnant in a gorgeous monochrome shift dress.
Marvin and Rochelle Humes, Phillip Schofield, Ashley Roberts, Tess Daly, Vernon Kay, Leigh Francis, Stephen Mulhern, Ben Shepherd and Paddy McGuinness were also there to see Dec marry the woman of his dreams.
Earlier in the day, joker Dec tweeted: "Morning! I know I've got somewhere to be today but I can't for the life of me remember where..."
He later posted a picture of Ant driving with the message: "Slow down man, what's the hurry!?"
Slow down man, what's the hurry!?— antanddec (@antanddec) August 1, 2015
Dec proposed to Ali in November 2014 in Australia, ahead of the I'm A Celebrity... Get Me Out of Here! series.
The fabulous news came one year after they had confirmed they were dating.
TV presenter Dec was best man for Ant when he married make-up artist Lisa Armstrong in 2006.
Something tells us the best man speeches would be raucous...
A huge congratulations to the newlyweds!
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