The 32-year-old Seema crossed the Rio Games qualification standard of 61.00m at the Hartnell College Throwers Complex with her season's best effort of 62.62m.
She won the gold in the event and in the process pipped 2008 Olympic discus throw champion Stephanie Brown-Trafton of United States of America for the gold.
This will be Seema's third Olympic Games appearance having taken part in 2004 and 2012 where she failed to get past the qualification round on both the occasions. She is the 19th Indian track and field athlete to have qualified for Rio Olympics.
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An elated Seema, who made her Olympic debut in 2004, said, "There is a sea change from 2004 up to now. Discus throwing is my passion. This time I didn't have much time to prepare, but I already have a gut feeling that Rio will be my best Olympic Games."