O'Sullivan (22), a graduate in physical education and commerce from the University of Otago, started in the job this week.
There were nine applicants for the job left vacant when Kellie Palmer shifted to Melbourne earlier this month.
The number of athletes competing in Otago increased during the seven years Mike Weddell had the job.
He now has the role of CoachForce manager with Sport Otago and oversees the work of the three CoachForce development officers in athletics, cycling and hockey.
Swimming was also in the system but withdrew last year.
Sport Otago is expected to fill the vacancy with another sport later this year.
The CoachForce officers have played a significant role in helping Otago athletics buck the national trend of declining numbers in the sport, increasing numbers and improving standards.
They are working closely with Des Smith, the chief executive of the Otago secondary schools sports association, to co-ordinate visits to schools.
O'Sullivan wants to enhance the quality of athletics in Otago by increasing the standard of coaches and the number of competitors.
She will be running coaching courses in schools and will hold a development day in August for pupils preparing for the New Zealand secondary schools championships in December.
O'Sullivan has highlighted the transition from secondary school to university study and employment as a key area she must work on "This is a time when people dabble in a lot of different things and can drop out of the sport,"she said.
A criticism of the CoachForce programmes controlled by sports trusts throughout the country is the short time the officers stay in the job.
The average time is only 18 months.
Athletics Otago was fortunate to have Mike Weddell stay in the job for seven years before being promoted to the top job.
He was able to gain the confidence of schools and sports clubs and thus boost the sport.
The two other athletics development officers in Otago both stayed for short periods.
O'Sullivan has given an undertaking to Sport Otago that she will remain in the job for at least two years.
She has had a long involvement in athletics since joining the Ariki children's section 12 years ago.
Her specialty events have been the long, triple and high jumps.
She has competed in these events at national championships.
O'Sullivan, who first competed for Otago in junior grades in 1998, has a best long jump of 5.10m and triple jump of 10.27m.
Her best performance at a national championships was seventh in the high jump at the New Zealand Secondary Schools Championships when she was a pupil at Kavanagh College.
"I like athletics because you can train in your own time, and also have the social side of the sport at the track," she said.
O'Sullivan comes from a sports-mad family.
Brother Tim plays senior cricket for University-Grange and her mother, Margaret, has operated the wind gauge at the Caledonian Ground for the past eight years.
O'Sullivan also dabbles in other sports.
She has played netball for University-Albion and still plays basketball for Ajax.
