The spacecraft's first perihelion -- the point in the orbit closest to the sun -- was about half the distance between the sun and Earth.
The probe made its closest approach at around 3.35 a.m Eastern standard time (07.35 UTC), Daniel Müller, the European Space Agency's Solar Orbiter project scientist, told CNN.
Müller said images taken with telescopes aboard the probe, which will be released in mid-July, will be the closest images of the sun ever captured.
The Solar Orbiter, whose mission is a joint collaboration between the European Space Agency and NASA, was launched in February to study the sun.
"We have never taken pictures of the sun from a closer distance than this," Muller said.
Solar Orbiter is equipped with 10 instruments that can capture observations of the sun's corona (which is its atmosphere), the poles and the solar disk, or circular visible surface of the sun. It also has instruments to measure the sun's magnetic fields and solar wind, or the energized stream of particles emitted by the sun that reach across our solar system.
Understanding the sun's magnetic field and solar wind are key because they contribute to space weather, which affects Earth by interfering with networked systems like GPS, communications and even astronauts on the International Space Station.
The sun's magnetic field is so massive that it stretches beyond Pluto, providing a pathway for solar wind to travel directly across the solar system.
"Our ultraviolet imaging telescopes have the same spatial resolution as those of NASA's Solar Dynamic Observatory (SDO), which takes high-resolution images of the sun from an orbit close to Earth. Because we are currently at half the distance to the sun, our images have twice SDO's resolution during this perihelion," Muller said in a statement.
Solar Orbiter has now started its cruise phase. In this phase, the spacecraft will get even closer to the sun's surface, around 42 million kilometers (26 million miles) -- closer than Mercury.
The spacecraft's four in-situ instruments -- those physically exposed to the outside environment -- will already be fully operational and will measure the properties of solar wind along its path. These four instruments provide a way of "touching" the environment around the spacecraft, while the other six provide what is called remote sensing.
"After one final swing-by at Earth in November 2021, Solar Orbiter will get closer to the sun than Mercury, our innermost planet," Muller told CNN via email. "The mission will then use Venus' gravity repeatedly to leave the ecliptic plane of the solar system and ultimately image the sun's uncharted polar regions for the first time," he added.