Elmore Smith was drafted by the Buffalo Braves in the 1st round (3rd pick) of the 1971 NBA Draft on March 29, 1971.
In his first season, Smith averaged 17.3 points per game and 15.2 rebounds per game, playing alongside Bob Kauffman, and was named to the NBA All-Rookie Team. His rebounding average for that season is the eighth-highest ever recorded by an NBA rookie.
In 1972–1973, he averaged 18.3 points and 12.4 rebounds for the Braves. Then, on September 12, 1973, he was traded by the Braves to the Los Angeles Lakers for Jim McMillian.
With the Lakers in 1973–74, Smith averaged 12.5 points with 11.2 rebounds and a league leading 4.9 blocked shots. The 1973–1974 season was the first in which blocked shots were officially recorded by the NBA, and Smith set a still-standing league record of 17 blocks in a game against Portland on October 28, 1973.
In 1974-75 Smith averaged 10.9 points and 10.9 rebounds with 2.9 blocks for the Lakers. On June 16, 1975, Smith was part of a historic trade. He was traded by the Los Angeles Lakers with Junior Bridgeman, Dave Meyers and Brian Winters to the Milwaukee Bucks for Kareem Abdul-Jabbar and Walt Wesley.
After 34 games with Milwaukee in 1975–76, Smith was traded on January 13, 1977, with Gary Brokaw to the Cleveland Cavaliers for Rowland Garrett, a 1977 1st round draft pick (Ernie Grunfeld was later selected) and a 1978 1st round draft pick (George Johnson was later selected).
In 1976–77, Smith averaged 12.5 points, 8.4 rebounds and 2.2 blocks for the 43–39 Cavaliers under Coach Bill Fitch.
Smith was plagued by a knee injury, that required surgery, and played in only 24 games for Cleveland in 1978–79, the last of his career.
Smith is best remembered for his shot-blocking, earning him the nickname "Elmore the Rejector". He led the league in total blocked shots twice (in 1974 and 1975), and holds the NBA record for most blocked shots in a game since 1973, with 17. He achieved this mark against the Portland Trail Blazers on October 28, 1973, while playing for the Lakers. Smith's average of 4.85 blocks per game from the 1973–74 season (the first season blocked shots were officially recorded in the NBA) is the third highest ever. He was also a skilled rebounder, and he averaged a double-double (13.4 points, 10.6 rebounds) over the course of his career.