It landed safely back at the Mojave Air and Space Port as a crowd of hundreds of people cheered.
"What a fantastic first flight", said Jean Floyd, CEO of Stratolaunch.
The aircraft constructed and designed by Stratolaunch has a record breaking 385-foot wingspan and has been 8 years in the making.
The twin-fuselage jet, which has six engines and a wingspan of 385ft from tip to tip, flew up to 17,000ft and reached speeds of around 170mph while its performance and handling qualities were evaluated.
Stratolaunch was developed by Northrop Grumman division Scaled Composites for Stratolaunch Systems Corporation, a company founded in 2011 by American billionaire and Microsoft co-founder Paul G. Allen. We got running down the runway, did our rotation and the airplane very nicely and smoothly rotated. "It definitely was ready to fly and wanted to fly and climbed out quickly".
Mr Thomas said there were "a few little things that were off-nominal but really for a first flight it was spot on".More news: Bottas keeps Mercedes on top in final Chinese GP practice
More news: Four injured after nightclub shooting in Melbourne
More news: Cargo agent seizes Jet Airways plane in Amsterdam for dues
It is created to carry as many as three satellite-laden rockets under its wings, which stretch about 117 meters. The dual-fuselage Stratolaunch is created to fly at an altitude of 35,000 feet, where it can drop rockets that ignite their engines and boost themselves into orbit around the planet.
At an altitude of 35,000 feet (10,668 meters), the rockets would be released, ignite their engines and soar into space.
It's powered by the same type of engines used by Boeing 747s, and is created to take off at a maximum weight of 1.3 million pounds (589,676 kilograms).
The previous wingspan leader was Hughes' second world war-era eight-engine H4 Hercules flying boat, which was nicknamed the Spruce Goose.
Stratolaunch originally touted this jet as the world's biggest aircraft, but toned down that statement this weekend referring to it as the "world's largest all-composite aircraft".
Its wings stretch about 97.5-meters and can still be seen today at an aviation museum in Oregon. The plane has two fuselages each with its own cockpit-though only one is needed to fly-6 Pratt & Whitney engines, usually found on Boeing 747s, and 28 wheels for its landing gear.