The world's biggest fast food chain reported net profit of $1.1bn (Â£763m), compared with $811.5m last year.
Like-for-like sales increased by 6.2%, boosted by an extra trading day because of the leap year.
Sales rose by a better-than-expected 5.4% in the US and 6.2% globally.
Its established markets including the UK and Australia posted a 5.2% jump.
Last October McDonald's started serving its breakfast menu after 10:30am in the US in response to customer demand, and simplified restaurant operations.
Chief executive Steve Easterbrook said: "Customers in the US are noticing a difference." The chain would continue with its turnaround plan for at least another two quarters before moving to a longer-term strategy, he added.
Revenue fell by 1% to a better-than-expected $5.9bn, but that was the smallest decline in seven quarters.
McDonald's, which also has been closing poorly performing outlets, selling company-run restaurants to independent operators and cutting spending, said total operating costs fell nearly 10%.
Shares were flat at $125.85 in New York and have risen 29% in the past 12 months, making the company worth $108bn.
McDonald's profits jumped by 35% in the first three months of the year, boosted by the continued popularity of its all-day breakfast and cut-price offers in the US.