The San Jose, Calif., company's shares fell 10% to $58.51 in after-hours trading.
For Q2 ended Jan. 31 the cybersecurity company reported adjusted earnings of 9 cents a share on revenue of $101.2 million.
The company had been expected to report adjusted earnings of 3 cents a share, on sales of $99 million, based on a FactSet survey of 18 analysts.
Zscaler forecast fiscal-third-quarter non-GAAP earnings per share of 1 cent to 3 cents on revenue of $105 million to $107 million.
Analysts had been predicting non-GAAP earnings of 4 cents on sales of $104.5 million, according to FactSet.
For the full fiscal year, Zscaler forecast total revenue of $414 million to $417 million and non-GAAP earnings per share of 14 cents to 16 cents, assuming 139 million shares outstanding.
"Momentum is continuing to build across our business as our customers embrace and accelerate their cloud transformation," said Jay Chaudhry, chairman and CEO of Zscaler, in a statement.
Elsewhere Thursday, cybersecurity stocks ended mixed.
The Nasdaq Composite Index fell 66.21 points, or 0.67%, to 9,750.96.
Fourteen cybersecurity stocks outperformed the Nasdaq Composite while three lagged.