The spacecraft passed the current record of 26.55 million miles from the Sun's surface on October 29, as calculated by the Parker Solar Probe team, NASA said in a statement on Monday.
The previous record for closest solar approach was set by the German-American Helios 2 spacecraft in April 1976.
As the Parker Solar Probe mission progresses, the spacecraft will repeatedly break its own records, with a final close approach of 3.83 million miles from the Sun's surface expected in 2024.
"It's been just 78 days since Parker Solar Probe launched, and we've now come closer to our star than any other spacecraft in history," said Project Manager Andy Driesman from the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland.
"It's a proud moment for the team, though we remain focused on our first solar encounter, which begins on October 31," Driesman added.
The Parker Solar Probe team periodically measures the spacecraft's precise speed and position using NASA's Deep Space Network or DSN.
Parker Solar Probe will begin its first solar encounter on October 31, continuing to fly closer and closer to the Sun's surface until it reaches its first perihelion -- the point closest to the Sun -- on November 5.
"The spacecraft will face brutal heat and radiation conditions while providing humanity with unprecedentedly close-up observations of a star and helping us understand phenomena that have puzzled scientists for decades," said NASA.
Earlier this month, the probe successfully completed its first flyby of Venus at a distance of about 1,500 miles.
Throughout its mission, the probe will make six more Venus gravity assist and 24 total passes by the Sun.