The Danish company finished installing the last of three jackets, with a combined weight of 22,000 tonnes, at the Culzean field on Thursday.
It said the installation work had been completed "on time and on budget".
Culzean is expected to produce 60,000-90,000 barrels of oil equivalent per day at plateau production.
Maersk has said the field, which lies about 145 miles east of Aberdeen, could meet 5% of UK gas demand by 2020-21.
Culzean project director Martin Urquhart said: "With the foundation of the Culzean installation firmly in place and waiting, focus is now fixed on finalising the construction of the three topsides and the Floating, Storage and Offload (FSO) vessel Ailsa.
"We have just celebrated the completion of the deck stacking of the topsides and the sail away of these structures is on schedule for next year.
"Their installation will take us to the beginning of the hook-up and commissioning campaign, the final step before first gas is delivered in 2019."
Maersk Oil chief executive Gretchen Watkins said: "Culzean was sanctioned less than two years ago and already we've progressed the project over the halfway mark.
"We're continuing to hit our milestones on time and this progress means we're on track to deliver first gas in 2019."
Maersk Oil is the field's operator, with a 49.99% stake. Its co-venturers are BP (32%) and JX Nippon (18.01%).
Maersk Oil has announced it is on track to deliver first gas from a major North Sea field in 2019 after completing foundation work at the development.