Osaka, 22, won the tournament on Saturday by coming from behind to beat the Belarusian Victoria Azarenka in a thrilling three-set final.
Having produced some of the best tennis of her young career on the court to seal her third Grand Slam title, off it Osaka also made a statement at this year's tournament.
In each of her seven matches, she wore a face covering displaying the name of a different Black victim of alleged police or racist violence in the US -- from Breonna Taylor in her first round-match against Misaki Doi to Tamir Rice in the final against Azarenka.
"I feel like the point is to make people start talking," Osaka said.
Taylor, an EMT and aspiring nurse, was killed in her own home in March. Three plainclothes Louisville police officers executing a "no-knock" warrant returned gunfire after Taylor's boyfriend had fired a warning shot because he thought he was shooting at intruders.
After wearing Taylor's name, Osaka revealed she had seven masks to wear throughout the tournament and had started with Taylor's name "because she was most important."
She told reporters: "I'm aware that tennis is watched all over the world, and maybe there is someone that doesn't know Breonna Taylor's story. Maybe they'll like Google it or something.
"For me, just spreading awareness. I feel like the more people know the story, then the more interesting or interested they'll become in it."
McClain, a 23-year-old massage therapist, was stopped by three officers in the Denver suburb of Aurora last August as he was walking home from a convenience store with an iced tea.
McClain was placed in a carotid hold, which restricts blood flow to the brain, the Adams County District Attorney said. A police news release had said McClain had "resisted contact" with officers before a struggle ensued. The DA's letter said paramedics arrived at the scene and administered ketamine, a powerful anesthetic. Three days later McClain was declared brain dead.
"For me, I think when I heard about (McClain's) story it was very hurtful," Osaka said following her second-round victory against Camila Giorgi.
"No one can really paint the narrative that he was a bad guy because they had so many stories and so many warm-hearted things to say about him."
Osaka wore Arbery's name on her face mask as she walked out for her third-round match against Marta Kostyuk.
Arbery, a 25-year-old unarmed Black man, died after he was chased by two White men while jogging in Brunswick, Georgia. Arbery and one of the men, Travis McMichael, struggled over the latter's shotgun and Arbery was shot three times, authorities said.
The pair face murder charges, along with another man who filmed the incident. All three pleaded not guilty in July.
Osaka told reporters after the game that she had been "touched" by the response she had so far received for wearing the masks during her US Open campaign.
The world No. 9 was almost moved to tears after she was shown messages from the families of Arbery and Trayvon Martin, a 17-year-old who was fatally shot by a neighborhood watch volunteer in Florida in 2012 as he walked home from a convenience store carrying iced tea and Skittles.
"I'm not sure what I would be able to do if I was in their position," said Osaka, who displayed Martin's name following her win against Anett Kontaveit.
"I feel like I'm a vessel at this point in order to spread awareness and it's not going to dull the pain, but hopefully I can help with anything that they need."
The death of Floyd, the fifth name Osaka wore as she contested her third grand slam quarterfinal, sparked protests across the United States and worldwide.
Floyd, an unarmed Black man, died in Minneapolis after an officer, who was called because a store owner believed Floyd had used a counterfeit bill to pay, pinned him to the ground by kneeling on his neck for several minutes.
Castile was fatally shot in July 2016 by Minnesota police officer Jeronimo Yanez during a traffic stop.
Yanez was later found not guilty of second-degree manslaughter and also acquitted of two counts of intentional discharge of a firearm that endangers safety.
Castile's death gained widespread attention after his girlfriend broadcast the shooting's aftermath on Facebook Live.
Rice, a 12-year-old boy, was killed by police gunfire in Cleveland, Ohio in November 2014 while he was holding a toy replica pistol.
Video footage showed Timothy Loehmann, who was then a trainee, arriving in a squad car that was driven by officer Frank Garmback. The car moved close to Rice and less than two seconds later, Loehmann shot the boy.
The two officers both said in written statements in 2015 they thought Rice was pulling out a real gun from his waistband. A grand jury declined to indict either of the officers.
In 2016, the city of Cleveland said it would pay $6 million to settle a federal lawsuit filed by Rice's family.