Emirates will fly a second daily service to Seattle from July 7.
The carrier will operate new flights EK227/228 with a B777-200LR aircraft.
Outbound service EK227 will depart Dubai at 0315 and arrive in Seattle at 0655, while return service EK228 will leave Seattle at 0940 and land in Dubai at 1055 the next day.
The existing service sees flight EK229 depart Dubai at 0935 and arrive in Seattle at 1255, with return flight EK230 leaving Seattle at 1740 and landing in Dubai at 1855 the next day.
Emirates is also launching a daily service to Orlando, again utilising a B777-200LR.
From September 1, flight EK219 will depart Dubai at 0350 and arrive in Orlando Terminal B at 1140. Return flight EK220 will leave Orlando at 1420 and land in Dubai at 1230 the next day.
Orlando will be Emirates' tenth US destination.
Tim Clark, president of Emirates, said: "As a growing region, we believe that our service will facilitate further growth for both Orlando as well as central Florida by connecting the city with our global network of 145 destinations across 80 countries."
Last week, Emirates opened a lounge at Los Angeles International airport (see news, March 19).