Sargent was drafted by the Los Angeles Kings with the 48th pick in the 1974 NHL Entry Draft and joined the Kings in 1975 after excelling for the United States national hockey team in the 1973 Ice Hockey World Championship and 1974 World Junior Ice Hockey Championships tournament, where he was voted most valuable defenseman. He was named the Kings outstanding newcomer after his rookie year. He was also a member of the US team at the inaugural 1976 Canada Cup tournament and was voted the Kings defenseman of the year in 1976-77. In the 1977–78 season, Sargent tallied 54 points, had a plus/minus of plus 18 on a team that was minus 2 for the season. However, the Kings failed to re-sign Sargent and he became a free agent.