He designed several notable buildings, including the McDonnell Planetarium and GROW Pavilion at the Saint Louis Science Center, the Independence Temple of the Community of Christ church, the National Air and Space Museum in Washington, D.C., and the Abraham Lincoln Presidential Library and Museum in Springfield, Illinois.

Due to his family's Japanese heritage, he was nearly interned with other Japanese-Americans during World War II.

After serving in the U.S. Army from 1946 to 1947 and working as an architect in the Chicago office of Skidmore, Owings and Merrill from 1947 to 1951, Obata returned to St. Louis in 1951 to join the firm of Minoru Yamasaki (who would later design the World Trade Center towers), another Nisei architect.

Obata's design philosophy is "to provide spaces which are not only functional, but also enhance the quality of life for those who work and live in them.

Each project offers new potential for discovery, for understanding the site and program, and an opportunity to do a thoughtfully designed building that will bring meaning and enjoyment to the people who will occupy it.