"Everyone has an Apple phone but what they lack is a tie-in with business," Cramer said Monday on "Squawk on the Street," shortly after the deal was announced. "It's so big that people should pay more for both stocks."
Under the alliance, Apple will help build iPhone features, such as the Siri voice assistant, deeper into Salesforce mobile apps.
"I would say [it's the] best attempt to go into the enterprise because voice is everything," said Cramer, whose charitable trust owns shares of Apple.
Salesforce will also make tools so businesses that use its back-end technology to power their own apps can build better products with features specific to iPhones and iPads.
"This is very big when it comes to cooperation," said Cramer, host of "Mad Money."
Apple and Salesforce both have huge ecosystems of third-party software developers.
About 20 million developers make software for Apple devices, most of them focused on the consumer, while Salesforce has about 5 million developers who tap into its back-end systems to build business applications.
Cramer, who has interviewed Salesforce CEO Marc Benioff numerous times on "Mad Money," said Monday that Benioff has always been "one to partner with anybody" and is now "integral" to Apple.
"At times, Marc has said, 'You know what, Siri may not be as good as Amazon,'" Cramer said, referring to Amazon's voice assistant, Alexa. "Now, Siri is now on par with [Alexa]. This is a very significant deal."
— Reuters contributed to this report.