The plane covered about 14,200km (8,824 miles) when it touched down in Auckland, New Zealand on Wednesday.
The return flight to Dubai left around 22:20 local time (15:20 GMT), according to New Zealand media.
It was expected to be the world's longest non-stop commercial flight by duration as well, but landed too early.
The Auckland-Dubai portion was estimated to take around 17 hours and 15 minutes, but in the end took only 16 hours and 24 minutes, according to the New Zealand Herald.
The new route reportedly reduces the current travel time by three hours.
The inaugural flights were made by an A380, but the regular service will reportedly be carried out using the Boeing 777.
Long flights
A Qantas Dallas-Sydney flight which covers 13,800km is currently the longest flight by duration, clocking in at about 16 hours and 55 minutes.
But Emirates is determined to beat that record.
It plans to launch a Dubai-Panama City service later in March that will take 17 hours and 35 minutes.
Singapore Airlines used to fly Singapore-New Jersey, which took 19 hours. The firm announced last year it was planning to bring back the service in 2018.
-BBC