Dowling will take over from Davina McCall when the Endemol series returns next month.
Nolan claimed that the former Big Brother winner and ex-Ryanair air steward is "a huge talent waiting to burst on to the screens".
Writing in her Irish Herald column, Nolan said that Dowling's recent work on RTE's Wagon's Den showcased his ability to be "spontaneous, professional and naturally funny".
"It's been a long time coming. Yes, he has done tons of telly - from SMTV Live all those years ago, where he was a breath of fresh air alongside Cat Deeley and Tess Daly, to Brian's Boyfriends," she said.
"But his non-stop appearances on reality shows made me wonder if he was ever going to move away from being a professional reality junkie. This summer, he is taking on one of the biggest television shows ever in the UK."
Nolan continued: "So how on earth is he going to outdo Davina? As long as he doesn't try to mimic her in any way, he should be absolutely fine. It's Brian time, and he has the talent, the experience and the charm to make this show his own and bring his own career to the heights it deserves."
Celebrity Big Brother will air in August on Channel 5.
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Watch two short trailers for the new series of Big Brother below: