China is stepping up its years-long fight to root out corruption with the purge of sitting members of the politburo, the ruling Communist Party's decision-making body, with Ma the third member targeted in the past six months.
Ma, who also serves as the deputy leader of the central rural work leading group, is undergoing a disciplinary review and supervisory investigation, the Central Commission for Discipline Inspection said in a notice on Friday.
The anti-graft watchdog did not disclose any details regarding the case.
The investigation into Ma follows the probe of another politburo member and China's top general Zhang Youxia in January.
The expulsion of He Weidong from the ruling party for corruption last year reduced the 24-member politburo to 23.
Ma and Zhang remain members in name only while the investigations unfold.
Ma's most recent known public appearance was at the Communist Party Central Committee's Fourth Plenum in late October.
Since then, he has been absent from the state broadcaster's footage of several key events including the annual parliament meeting last month.
Ma, 66, holds a PhD in general mechanics and worked for nearly a decade in China's famed Harbin Institute of Technology, a university - now under US sanctions - in the country's northeast with deep ties to the military and aerospace sectors.
He entered China Aerospace Science and Technology Corporation (CASC), the People's Republic's main spacecraft and missile manufacturer, in the late 1990s and oversaw some of China's most important satellite and crewed space programs.
Elected as an academic in the International Academy of Astronautics in 2007, Ma was promoted to CASC's party chief before becoming director of China's National Space Administration and Atomic Energy Authority in 2013.
The scientist-turned-administrator's meteoric ascent in Chinese officialdom in the following years resulted in him serving as party chief of tech hub Shenzhen and governor of coastal economic powerhouse Guangdong.
In 2021, Ma was named party chief of Xinjiang, replacing Chen Quanguo who oversaw a security crackdown targeting ethnic Uighurs and other Muslims in the name of fighting extremism.
Ma's appointment was seen by some observers as the leadership's attempt to drive the vast border region forward after Chen's high-pressure campaign drew global backlash.
Ma was removed from his position in Xinjiang in July.
