He played in high school with another future NBA star, Gus Johnson, at Akron Central. Their powerful team went undefeated before losing to Middletown, led by Jerry Lucas, in the Ohio state high school playoffs. Passing on a scholarship offer to Ohio State, to avoid becoming Lucas's backup there, the 6'11" Thurmond chose Bowling Green. He was named a first-team All-American by The Sporting News in 1963, and was drafted by the San Francisco Warriors later that year.
When Chamberlain was traded back to Philadelphia's new franchise, the Philadelphia 76ers, Thurmond became the All-Star starting center Chamberlain said he could be. Among his many accomplishments, Thurmond still holds the regular season record for rebounds in a quarter with 18. He averaged 21.3 and 22.0 rebounds per game in the 1966-67 and 1967-68 seasons — season averages exceeded by only Bill Russell and Chamberlain in NBA history. Thurmond placed second to Chamberlain in the MVP balloting in the 1966-67 season, and averaged over 20 points per game each season from 1967-68 through 1971-72, and played in seven NBA All-Star Games while with the Warriors. However, while star players like Rick Barry and Jerry Lucas came and went, the Warriors were unable to win a championship with Thurmond at center. Thurmond was an excellent passing center and was well known as the best screen setter in the league for many years.
After retirement, Thurmond returned to San Francisco and opened a restaurant, Big Nate's BBQ, after a brief attempt at broadcasting. He sold the restaurant after 20 years, and currently lives in San Francisco with his wife, Marci. He has been given the title "Warriors Legend & Ambassador" by the Warriors organization.