CLPS in a statement didn't identify the customer or disclose terms of the deal.
Shares of CLPS at last check were trading at $15.13. Earlier on Wednesday the stock touched a 52-week high $19.78. The shares closed Tuesday's session at $4.90.
CLPS said its subsidiary in California had signed to provide "a well-known U.S. digital payment platform" with services including data analysis and payment risk management for its international business.
The two companies have cooperated for more than six years, and the client has now awarded CLPS a global contract, CLPS Chief Executive Matthew Tang said in a statement.
CLPS said it had been growing beyond the China market with new clients in the blue-chip financial-institution sector.
"This also aligns with our global strategy by leveraging our expertise in the financial industry with globally competitive IT services," Tang added.
"The pace of change across the payment industry has significantly accelerated in the span of the COVID-19 pandemic, which reshaped people's lives across the world," added Chief Operating Officer Henry Li.
CLPS is committed "to deliver comprehensive IT services to the client, ensuring safe and secured online payment transactions."