The plane reached a maximum altitude of 22,500 feet (6,860 meters), according to a representative for Stratolaunch.
The Independent reported that Roc has a wingspan of 117 meters, which is longer than an American football field.
The aircraft to previously hold the longest wingspan was the Antonov An-225 Mriya with 88.4 metres.
The aircraft is designed to carry and launch hypersonic vehicles, and is capable of lifting around 220 tonnes.
Additionally, the Stratolaunch Roc is powered by six Boeing 747 engines.
The flight marks the ninth trip the plane has taken overall and the second to carry Stratolaunch's Talon-A hypersonic test vehicle aloft.
Stratolaunch CEO and president Zachary Krevor said in a media release: “Our amazing team is continuing to make progress on our test timeline, and it is through their hard work that we grow closer than ever to safe separation and our first hypersonic flight tests.
"The thorough evaluation of release conditions will provide data to reduce risks and ensure a clean and safe release of Talon-A during future tests.
“We are excited for what’s ahead this year as we bring our hypersonic flight test service online for our customers and the nation.”
Perhaps the monster aircraft will soon be accessible to customers?
Stratolaunch Roc took its first trip in April 2019 and lasted 150 minutes, reaching a maximum speed of 175 miles per hour and a peak altitude of 15,000 feet (4572 meters), as per Space.com.
Verge reported that test pilot Evan Thomas said the trip fulfilled all of the company's expectations.
He revealed: "The flight itself was smooth, which is exactly what you want a first flight to be.”
Thomas added: “It flew very much like we had simulated and like we predicted.”
The company hopes that one day they will be able to use the mega plane for easy and accessible transport to space, similar to the method used by Virgin Orbit.
The private space company was launched in 2011 by Microsoft co-founder Paul Allen.
It was created to develop a new air-launched space transportation system, with its corporate headquarters located in Seattle, Washington.