Mission controllers at NASA's Jet Propulsion Laboratory (JPL) in Southern California received data that confirmed the historic milestone, the US space agency said in a statement.
The core is now enclosed in an airtight titanium sample tube, making it available for retrieval in the future.
A Perseverance rover retrieved the rock sample at its second attempt on September 1, after failing in its first attempt in early August. While Perseverance, using its 2-meter-long robotic arm, drilled a hole on Mars, it could not collect and store as intended in its first attempt.
"Our Perseverance team is excited and proud to see the system perform so well on Mars and take the first step for returning samples to Earth," said Larry D. James, interim director of JPL.
The sample-taking process began on September 1, when the rotary percussive drill at the end of Perseverance's robotic arm cored into a flat, briefcase-size Mars rock nicknamed "Rochette".
After completing the coring process, the arm maneuvered the corer, bit, and sample tube so the rover's Mastcam-Z camera instrument could image the contents of the still-unsealed tube and transmit the results back to Earth.
After mission controllers confirmed the cored rock's presence in the tube, they sent a command to complete the processing of the sample.
On Tuesday, at 12.34 a.m. EDT, Perseverance transferred sample tube serial number 266 and it's Martian cargo into the rover's interior to measure and image the rock core. It then hermetically sealed the container, took another image, and stored the tube.
"Getting the first sample under our belt is a huge milestone," said Ken Farley, Perseverance Project Scientist at Caltech.
"When we get these samples back on Earth, they are going to tell us a great deal about some of the earliest chapters in the evolution of Mars.
But however geologically intriguing the contents of sample tube 266 will be, they won't tell the complete story of this place. There is a lot of Jezero Crater left to explore, and we will continue our journey in the months and years ahead," he added.
Through the Mars Sample Return campaign, NASA and ESA (European Space Agency) are planning a series of future missions to return the rover's sample tubes to Earth for closer study. These samples would be the first set of scientifically identified and selected materials returned to our planet from another.
The Mars 2020 Perseverance mission is part of NASA's Moon to Mars exploration approach, which includes Artemis missions to the Moon that will help prepare for the first human exploration mission to the Red Planet.