The Briton finished more than two minutes ahead of Poland's Anna Harkowska in Nottwil, Switzerland.
Storey can win a 17th title when she rides in Saturday's road race.
"It's a massive relief to win," said the 37-year-old, who is targeting further Paralympic success at next year's Games in Rio de Janeiro.
Storey is Britain's most decorated female Paralympian with 22 medals.
She has won 11 gold, eight silver and three bronze medals in both cycling and swimming across six Paralympics.
She won four golds at the 2012 Games in London and has now won 21 world titles across both sports.
Storey began her sporting career in the pool, winning six medals at the 1992 Paralympics before switching to cycling in 2005.

Steve Williams, of Flat Iron Heritage, contacted his local MP, Lindsay Hoyle, after families were blocked from visiting the Chorley Pals Memorial Site at Serre-les-Puisieux.
He claims they were obstructed by a farmer who owns land near the cemetery.
The BBC tried to contact Jean Louis Legrand but could not get a reply.
To reach the Pals' Battalions memorial at the Sheffield Memorial Park, which is owned by Sheffield City Council, visitors must use an unmade public right of way that crosses land owned Mr Legrand.
The path is owned by the town of Serre whilst the park itself is looked after and maintained by the Commonwealth War Graves Commission (CWGC).
The commission's Director General Victoria Wallace said: "We are very concerned about the situation at Serre, and urge any visitors encountering hostility or harassment to report it to the local authorities.
"We are working with the French government and local authorities to find long-term solutions, but meanwhile we urge caution when visiting, and we ask visitors not to inflame the situation by ignoring the parking restrictions."
The dispute has forced Flat Iron Heritage to cancel visits.
Mr Williams, who has been making an annual trip to the area since 2002, said the situation was getting worse.
He said it has caused a "great deal of distress" to those travelling to visit the graves of loved ones.
Labour MP for Chorley Mr Hoyle has written to Foreign Secretary Boris Johnson asking his department to investigate.
Sheffield Memorial Park
Dame Sarah Storey claimed the 16th world title of her cycling career with gold in the time trial at the Para-cycling Road World Championships.
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Foreign Secretary Boris Johnson has been asked to investigate claims that soldiers' relatives have been stopped from visiting their graves in France.