This allows users to spend money from Square Cash anywhere that accepts Apple Pay with the tap of their mobile device.
Square CEO Jack Dorsey and Apple Vice President Jennifer Bailey, who runs Apple Pay, unveiled the new partnership at the Code Commerce conference in San Francisco on Tuesday evening.
"People just want a more modern interface to their finances," said Dorsey, who is also co-founder and chief executive of Twitter.
The goal is to drive adoption of both services and give consumers better, more secure options than they currently had with credit and debit cards, the executives said. Many people hate the new chip cards because of the time it takes to process transactions, Dorsey added.
"The benefit to Apple Pay is our experience is much better and it's much faster," said Bailey, who noted that Apple Pay is now accepted by 35 percent of U.S. merchants.
"We see this growing," said Dorsey. "The rest of the world is mainly tap."
Apple revealed in September that Apple Pay transactions had grown 500 percent over last year.
"Our goal is to replace the wallet," Bailey said.