SBI will pay $1.70 per share for the 4.8 million outstanding shares of Razorfish.
The companies expect the deal to be completed in early 2003.
Ned Stringham, SBI's president and chief executive officer, said the acquisition of Razorfish completes his company's strategy to build an industry-focused professional services firm for Internet-driven businesses.
He said Razorfish's people, customer relationships and service offerings are an excellent fit with SBI's business.
The deal expands SBI's client list, increases its workforce from 700 to about 900 employees and moves it into more US cities.
Razorfish chief executive officer Jean-Philippe Maheu, said the deal is good for his company's clients, as well as for its employees.
Maheu said clients would be better served by the combination of SBI's technical skills, especially in back-end transactional systems and Razorfish's skills in building extended enterprise portals. The combined company will offer more growth opportunities for its employees, he added.