Using his bare hands and without a harness, Robert clambered up the building located in the central business district and secured a large banner on the building's exterior.
The sign positioned China's flag in the left hand corner with Hong Kong's flag on the right side.
Underneath was a yellow hand shaking a red hand on a white background to signify peace.
Robert's climb up to the top of 283-meter building owned by Hong Kong's richest man Li Ka-shing quickly attracted a crowd of pedestrians.
Police said they arrested him after the stunt, which took about an hour in total.
Ten weeks of increasingly violent confrontations between police and protesters have plunged Hong Kong into its worst crisis since it reverted from British to Chinese rule in 1997, and have presented the biggest popular challenge to Chinese President Xi Jinping since he came to power in 2012.
It was the third time Robert climbed the Center.
He was banned from climbing buildings in the former British colony for a year last August.
His ban ended two weeks ago.
Robert is well-known for climbing up urban high-risers and has done so in countries including France, Indonesia and the Philippines earlier in the year, as well as London in 2018.