The International Building Press (IBP) judges praised Hahn for her "versatility, maturity and an ability to dig out a story and raise awareness on subjects of importance".
Hahn praised for "critical, balanced, provocative and revealing pieces"
The judges were particularly impressed with Hahn's work for Dezeen's Carbon Revolution series, which explored how the material could be removed from the atmosphere and put to use on earth.
"The writer avoids swallowing the PR line and digs deeper giving critical, balanced, provocative and revealing pieces," the judges said. "Design that produces carbon-neutral buildings runs through this submission."
Hahn joined Dezeen as a reporter at the end of 2019. The new journalist category recognises writers that have been covering the built environment for less than two years.
Dezeen honoured at IBP Awards for fifth year in a row
Hahn collected the prize at an awards ceremony in London last week where Dezeen was also shortlisted in the editorial brand of the year category.
Dezeen's editor-in-chief Marcus Fairs was also shortlisted in the architecture writer and construction writer of the year categories, while Dezeen's features editor Nat Barker was shortlisted in two further categories for his previous role at the trade magazine Inside Housing.
It is the fifth year in a row that Dezeen has been honoured at the IBP National Journalism Awards, which recognises journalists and media brands covering the built environment.
Last year, Dezeen's Virtual Design Festival was named event of the year and Fairs won the digital leadership award. Dezeen was named editorial brand of the year in 2019, having won the digital service of the year categories twice in a row in 2018 and in 2017.
Nine awards for Dezeen this year
Hahn's IBP accolade is the ninth honour Dezeen has received this year.
Dezeen was named Best Small Digital Publisher of the Year and scooped three other prizes at the AOP Digital Publishing Awards in September.
Fairs took home prizes in the Specialist Editor of the Year and Independent Editor of the Year categories at the BSME Awards, while Dezeen's in-house creative studio Dezeen Studio was named Best Video Team at the BSME Talent Awards, which recognises teams and individuals without an editor title.
Earlier this year, Dezeen also won a People's Voice Webby Award for the Out of the Box competition with Samsung, which challenged contestants to create objects for the home by repurposing television packaging.