Background: Fathering and father involvement is critical to the formation, stability, and wellbeing of children and families in society. However, the contemporary nature of fathering and families is changing, especially for emigrant minority populations. Approximately 7% of people in New Zealand are of Pacific descent. While recognised, the importance and impact of the role of fathers has received little empirical attention among this population. This paper examines the relationship between father involvement and their child’s behaviour outcomes amongst a birth cohort of Pacific children and fathers in New Zealand. Methods: A birth cohort was established in 2000 from births at Middlemore Hospital in South Auckland where at least one parent was identified as being of Pacific ethnicity and a New Zealand permanent resident. This included 1376 mothers, 825 fathers, and 1398 children at baseline. At the 6-years measurement wave, father involvement was measured using the Inventory of Father Involvement (IFI), and child behaviour measured using the Child Behaviour Check-list (CBCL). Internalising and externalising behaviour was related to father involvement in crude and adjusted logistic regression and generalised estimating equation models. Results: 571 Pacific fathers participated at the 6-years measurement wave; most of Samoan (42.9%) or Tongan (33.5%) ethnic identification. Overall, 190 (32.1%) children exhibited clinical or board-line internalising and externalising behaviour. Self-reported father involvement was generally high, but lower involvement was significantly related to increased odds of internalising (adjusted odds ratio [aOR] approximately 1.9, p<0.001) and externalising (aOR approximately 4.0, p<0.001) behaviour. Conclusion: Father involvement was significantly associated with child behaviour in Pacific families within New Zealand. Strategies that promote and enable increased father involvement may reduce negative child outcomes; common to a disproportion of Pacific families.