The Olympic silver-medallist Indian won 21-7 21-7 in the final that lasted just 38 minutes.
Two years after being robbed off the gold by Okuhara in an epic 110-minute final at Glasgow that was considered as one of the greatest battles in badminton history, Sindhu finally exorcised the ghost of that heart-wrenching loss with a completely dominating win over the same opponent.
"Last time, I lost in the final, before that also I lost in the final, so it is a very important win for me. I want to thank the crowd for supporting me. I won it for my country and I am very proud being an Indian," Sindhu said after the match.
"A big thanks to my coach Kim and Gopi sir and my supporting staff and I dedicate this win to my mom, it's her birthday today," she added.
It was third time lucky for Sindhu who had lost to Okuhara and Carolina Marin of Spain respectively in the 2017 and 2018 finals to settle for a silver twice.
With her fifth medal of the World Championships, the 24-year-old Indian was already one of the greatest ever women's singles players in the showpiece event's history. She had won a bronze each in the 2013 and 2014 editions.
Talking about her game plan, Sindhu said: "I am really happy, I have waited for this victory, and finally I've become world champion. A lot of credits to my coaches - Gopi sir and MS. Kim and also to my parents as well, my support staff and all my sponsors who believed in me. I've no words to express because I was waiting, last year it was silver, before that it was silver and then finally I'm world champion, I'm really very happy".
Sindhu is now the joint highest medal winner in women's singles in the World Championships history with former Olympic champion Zhang Ning of China who has won an identical 1 gold, 2 silver and 2 bronze between 2001 and 2007.
Prakash Padukone became the first Indian to win a medal in World Championships with a men's singles bronze in the 1983 edition while Saina Nehwal bagged a silver and a bronze in 2015 and 2017 respectively in women's singles.
Jwala Gutta and Ashwini Ponnappa also won a bronze in women's doubles in 2011 while B Sai Praneeth was the latest to join the club as he settled for a bronze in the men's singles in this edition on Saturday.
Sindhu, who has also won a silver each in the 2018 Commonwealth Games and 2018 Asian Games, was a in different class today as she toyed with her Japanese opponent in all departments of the game.
The fifth seeded Indian, who enjoyed a 8-7 head-to-head lead over third seeded Okuhara ahead of Sunday's contest, was simply unstoppable as she dished out an attacking game right from the start to race to 8-1 lead.
The Indian targeted the deep corners and unleashed her big smashes to gather points at will.
A precise net shot helped Okuhara to snap Sindhu's run of straight eight points but the Indian quickly got the control back when Okuhara went wide and then unleashed two good-looking smashes to enter the break with a massive 11-2 lead.
Okuhara tried to step up the pace but an alert Sindhu was up to the task. The Indian targeted Okuhara's forehand corner to take two more points.
Sindhu used her height to produce those attacking clears which Okuhara could not negotiate. At 16-2, Sindhu committed a couple of unforced errors before again taking control of the match.
Sindhu eventually grabbed as many as 13 game points when Okuhara went long and she sealed the first game with a body blow which her rival sent out.
In the second game, Sindhu continued her rampaging form, grabbing two quick points before Okuhara earned a point with a cross court smash.
Okuhara had no answer to Sindhu's razor sharp returns. The Indian made the Japanese run to the deep corners with her acute angled returns and then swiftly followed them at the net to make life difficult for her opponent.
Okuhara seemed clueless as she ended up hitting the nets or missing the lines to allow Sindhu grab 11-4 lead at the interval.
Nothing changed after the breather as a relentless Sindhu kept her stranglehold on the Japanese, who crumbled under pressure.
At 16-4, Sindhu made a couple of rare errors when she hit long but that did not matter as she pounced on a weak return from Okuhara and sent it to the backline and then left her rival stranded with another powerful smash.
Sindhu grabbed the match point when Okuhara went long again and sealed the title when another superb return before throwing her hands in the air in celebration.
With Sindhu's gold and Praneeth's bronze in this edition, Indian shuttlers also continued the six-year streak of winning at least one medal in the prestigious event.
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