Ramakrishnan joined Microsoft in 2012 as a Technical Fellow and CTO, Information Services and heads the Cloud and Information Services Lab (CISL) with members in Redmond, WA and Mountain View, CA. From 2006 to 2012, he was a Yahoo! Fellow. In 1999, he founded QUIQ, a company that developed innovative collaborative customer support and knowledge management solutions used by companies such as Business Objects, Compaq, National Instruments, Network Appliances, Sun Microsystems, and others, and served as the Chairman and CTO until 2003, when QUIQ was acquired by Kanisa.

At UW-Madison, his research was in the area of database systems, with a focus on data retrieval and integration, analysis, and mining, and is often done in collaboration with researchers in industry. He led the CORAL project, which developed and distributed the CORAL deductive system, and contributed to recursive query language extensions in the SQL:1999 standard. He and his group have developed scalable algorithms for clustering, decision-tree construction, and itemset counting, and were among the first to investigate mining of continuously evolving and streaming data. His work on query optimization has found its way into several commercial database systems, and his work on extending SQL to deal with queries over sequences has influenced the design of window functions in SQL:1999. None of this would have been possible without a great group of former students; of all his contributions, he is proudest of this list.