The chart star took the Best Music Programme title at the Radio Academy Awards in London which rewards the cream of the airwaves, beating a shortlist which also included Blur's Alex James.
Other notable names to triumph at the ceremony included Radio 5 live's Danny Baker, who won a gong at the event for the fourth consecutive year by taking the Speech Radio Personality of the Year prize.
East Midlands presenters Amy Voce and Sam Pinkham from Gem 103 pulled off a coup by beating big name fellow nominees such as Graham Norton and Chris Evans to take the Music Radio Personality of the Year title. The pair last year won the best breakfast show prize for smaller stations.
One of the plum awards, the much-prized category of the UK's top breakfast show was won this year by 95.8 Capital FM duo Dave Berry and Lisa Snowdon, ahead of figures such as Radio 5 Live's Rachel Burden and Nicky Campbell. Radio 1's Nick Grimshaw failed to even make the shortlist for the award.
Politicians Nick Clegg and Boris Johnson also shared in a prize, after the weekly shows in which they face the public on air took the evening's Special Award.
The deputy Prime Minister and the Mayor of London together with presenter Nick Ferrari and the rest of their LBC production team were given the title for the "innovative strand" of programmes.
Mr Johnson joked: "Well this is absolutely absurd. Of course I know I'm not really the recipient - I'm like an overweight Belgian tourist being propelled to the summit of this Everest by the skills of superior Alpinists, our LBC production team.
"I'd like to thank the efforts of the great Sherpa, Clegg, and the people of London who have listened in their dozens and called in, and to my fellow overweight Alpiniste, Nick Ferrari."
Organisers of the event recognised LBC's shows Call Clegg and Ask Boris for the "transformational effect" the programmes have had in putting commercial radio at the heart of the news agenda on a regular basis.
The judges' citation praised the team behind the shows for placing politicians "front of mic, hosting their own show, on a regularly scheduled basis, something never before attempted on UK radio".
Other big winners at the ceremony, staged at the Grosvenor House Hotel, included Radio 1's Greg James who landed his first prize from the Radio Academy Awards - known for many years as the Sonys, until the main sponsor withdrew after last year's event.
Comedian Frank Skinner whose Absolute Radio show was named Best Speech Programme, and 5 Live's Victoria Derbyshire was named Speech Radio Broadcaster of the Year.
Skinner was delighted but bewildered to win for a "speech" show.
He said: "Best speech programme? This is like the Very Hungry Caterpillar winning the Booker Prize. I really didn't expect that.
"I'd like to apologise to Absolute Radio who pay me to host a 'music show'."
A poem about an auction at a livestock market set to a musical score, Between The Ears: Mighty Beast, collected the Best Feature Or Documentary prize for Radio 3.
The event, hosted by Radio 2 presenter Chris Evans, saw the prize for Music Radio Broadcaster of the Year go to Radio 1's Zane Lowe. He last won the title three years ago.
Evans took a swipe at ITV's new Good Morning Britain host Susanna Reid as he opened the show, telling guests that she was "the former breakfast queen of British television".
As she later joined him on stage to present the Special Award, he teased her about her new show's failure to sparkle in the ratings: "The race is long. I'd check your contract."
But she kept her cool and told guests: "I'm mostly glad I came."
Cullum was not the only musician to land a prize tonight with rapper Scroobius Pip picking up the award for Best Specialist Music Programme for his XFM show.
BBC Radio 2 took the title of UK Station of the Year for the first time since 2005.
And its veteran Tony Blackburn, who hosts the Pick Of The Pops countdowns, was handed the honorary Gold Award which had already been announced in advance of the ceremony.
It was to honour his 50th year in radio and he became the first person to pick up the Gold Award on two occasions, the last being on the 25th anniversary of his broadcasting career.
Cullum was on holiday with wife Sophie Dahl and was unable to attend, but Evans said at one stage the jazz star had considered cancelling to attend the event.
His Radio 2 producer Karen Pearson said: "It's such a shame that Jamie's not here - he'd be leaping up and down."
Kaiser Chiefs frontman Ricky Wilson took the stage to present the award to Zane Lowe while wearing a patch over his left eye.
He explained: "I hurt myself filming the video for our new song. I poked it."
Accepting his prize, Lowe said: "That's all I'm here to do - to put the audience and music together, and I'm very grateful."
Collecting the UK station of the year award, controller Bob Shennan praised the station team and said: "They know how to make the good really popular, and the popular very, very good."
Blackburn received his award from fellow Radio 2 host Graham Norton who told guests: "My greatest pleasure at Radio 2 is every Saturday morning when Tony comes into our studio and he bounces in and we say 'how are you Tony, and he says 'still not arrested'."
Accepting the prize, Blackburn said that after so long it would be no surprise that thoughts turned towards retirement.
"I've been on the air for 50 years now and I got my family together last week and I said probably it's time I spent more time with you at home.
"And they all said to me 'we'd rather you didn't' so I've decided to go on for another 50 years."