Last year the university was controversially given consent to build the access road across Green Belt land to the park, which conducts academic research and provides space for hi-tech start-up companies.
It provides a direct link between the science park and the A44 Woodstock Road, taking traffic off Sandy Lane in Yarnton.
Residents in Begbroke and Yarnton opposed both the route finally adopted and an earlier proposal for a road through Yarnton.
University vice-chancellor ProfAndrew Hamilton officially opened the road on Wednesday.
He was driven along the road to cut a ribbon in the Autonomous Bowler Wildcat, a driverless robotic car, based on a Land Rover Defender, developed by Prof Paul Newman.
Prof Peter Dobson, academic director of the science park, said: “The road will trigger new building initiatives on the site and enable the university to lead the way with innovative developments that are so vital for economic recovery in the UK.”
Dr Caroline Livingstone, the manager of the science park, added: “The new road gives us direct access to the A44, between the Begbroke and Sandy Lane roundabouts, relieving Sandy Lane of our traffic both now and as activity expands in the future.
“We hope that this will be beneficial to the local community.”