The name Jack bumped out Liam for top boys' names of 2012 and Olivia beat Ruby for the title of the most popular girls' name.
In 2011, Ruby was the most popular girls' name, but that was bumped down to fifth place last year, as Olivia moved up from second to first spot.
For boys, in 2011 Liam was the most popular name, but that fell to fourth place last year, with Jack moving up from 10th.
Data released yesterday by the Department of Internal Affairs of names registered with Births Deaths and Marriages, shows Jack is back and as popular as ever.
From 2005 to 2009 the name sat at the top of the list, but fell off the top three list in recent years.
Jack Beckett, and his brother James, were named after their father, Dave Beckett's, two great-grandfathers.
Ms Dawson said she was surprised to hear Jack had topped the most popular names list for 2012.
"I thought it was quite old-fashioned," she said.
In the top 10 list for boys, Mason made the biggest leap, from 15th place in 2011 to fifth place last year.
For girls, the jump was not so dramatic, with Sophia pushing up from 15th in 2011 to ninth in 2012.
2012's popular names
Top 10 girls' names last year (2011 place in brackets)
1 Olivia (2)
2 Sophie (3)
3 Emily (9)
4 Charlotte (5)
5 Ruby (1)
6 Isabella (4)
7 Ella (7)
8 Amelia (10)
9 Sophia (15)
10 Ava (12)
Top 10 boys' names last year (2011 place in brackets):
1 Jack (10)
2 Oliver (3)
3 William (5)
4 Liam (1)
5 Mason (15)
6 Samuel (7)
7 Jacob (11)
8 Lucas (4)
9 Ethan (16)
10 Noah (6)