The award acknowledged excellence in client service and ''leading expertise'' in advising across a broad range of practice areas.
Downie Stewart Lawyers was selected from five finalists and was the only South Island firm to reach the finals.
It followed success for the firm in 2012 when it won the supreme award for employer of choice after being judged the best law firm to work for in New Zealand.
That was the first time the firm had entered the awards and this year was only the second, managing partner Gerard DeCourcy said.
Entering was an opportunity to measure against other firms and success meant acknowledgment for all the staff which was ''one of the nicest parts'', Mr DeCourcy, who accepted the award at a function in Auckland, said.
Both awards were very firm-oriented, applying to everybody in the firm, not just the partners or particular individuals, he said.
People were key to the firm's success and it had a ''great team'' delivering a high-quality service, in a happy workplace.
''And we are lucky enough to be able to do it all from beautiful Dunedin,'' he said.
Downie Stewart Lawyers was founded by William Downie Stewart in 1867.
The firm employed 30 staff with offices in both Dunedin and Balclutha.
It had several long-term staff and it had recently started formalising that long service, acknowledging the milestones of 15, 20 and 25 years.
The business had grown a lot in the past few years and, when it came to employment, it was about adding to staff numbers, rather than replacing.
''We don't have to replace staff very often at all,'' Mr DeCourcy said.
