Splunk Inc. reached a $1.05 billion deal to buy cloud-monitoring startup SignalFx Inc., a deal that would strengthen the cybersecurity and data-analytics firm’s offerings in the fast-growing cloud-computing sector.

“SignalFx will support our continued commitment to giving customers one platform that can monitor the entire enterprise application lifecycle,” Splunk Chief Executive Doug Merritt said in a statement.

Founded in 2004, Splunk—a play on the word “spelunking”—collects and analyzes data to help companies identify patterns, like customers’ beverage preferences, and detect anomalies, say fraud or a cyberattack.

“The future is clear,” Mr. Merritt said in a conference call with analysts. “Data represents the biggest opportunity and the biggest threat to businesses, governments and, frankly, to humanity.”

Splunk officials told analysts that Splunk has some customer overlap with San Mateo, Calif.-based SignalFx and that the target company’s software represents a “top tier asset to the things that matter” to clients. Closely held SignalFx was valued at nearly $500 million after a $75 million funding round that closed in May, according to a Dow Jones VentureSource estimate.