Djokovic heads the men's field with Spain's Rafael Nadal seeded second. In the women's draw, Osaka is ranked no 1 Serena Williams is no 8.
New York: World number ones and defending champions Novak Djokovic and Naomi Osaka were named as top seeds for the US Open on Wednesday.
Djokovic, who will be chasing a 17th Grand Slam singles title in New York next week, heads the men's field with Spain's Rafael Nadal seeded second.
Former world number one Roger Federer, seeking a 21st Grand Slam crown, is seeded third for the tournament.
The draw for the men's and women's singles takes place on Thursday.
In the women's draw, Osaka is ranked number one while 2018 runner-up Serena Williams is seeded eight.
Japanese ace Osaka won her first Grand Slam title in a controversial final victory over Williams last year and then followed it up with her second Slam at the Australian Open in January.
The two other reigning Grand Slam champions are seeded in the top four, with Australia's French Open champion Ashleigh Barty seeded second and Romania's Wimbledon champion Simona Halep seeded four.
Former world number one Karolina Pliskova of the Czech Republic is seeded third in the women's draw.