Objective: The objective of this study was to examine the duration of mechanical ventilation (MV) in days until the first successful extubation and the cumulative duration of MV until discharge of infants with gestational age (GA) <26 weeks. We also aimed to explore associations between early clinical variables and the cumulative duration of MV. Design and Setting: This population-based study analysed data reported to the Norwegian Neonatal Network on extremely premature infants admitted between January 1, 2013, and December 31, 2018. Results: A total of 406 infants were included, of which 293 (72%) survived to discharge. The proportion successfully extubated on their first attempt was 34% of the infants born at GA 22–23 weeks, 50% at GA 24 weeks, and 70% at GA 25 weeks. Median postmenstrual age (PMA) at the first successful extubation was 27 weeks. The median duration of MV was 35, 24, and 12 days for infants born at GA 22–23, 24, and 25 weeks, respectively. Male sex and low 5-min Apgar score were independent early predictors for prolonged MV duration adjusted for GA in regression analyses. Conclusions: Most of the infants born at GA 25 weeks were successfully extubated on the first attempt. However, half of the infants born <26 weeks experienced unsuccessful extubations, indicating a lack of useful clinical predictors of successful extubation. The median duration of MV in survivors was 4 weeks longer for infants at GA 22–23 weeks than for infants born at GA 25 weeks, while the difference in median PMA at the first successful extubation was 2 weeks.