Modrý was selected 179th overall in the ninth round of the 1990 NHL Entry Draft by the New Jersey Devils. He made his NHL debut with the Devils during the 1993–94 season. A trade to the Ottawa Senators in July 1995 was followed months later in March 1996 by a trade to the Los Angeles Kings. Modrý started seeing more playing time in the NHL and eventually became an NHL regular with the Kings, playing his first full season in 2000–01. The following season, 2001–02, saw Modrý set career highs in assists (38) and points (42) and play in the NHL All-Star Game. He scored a career high 13 goals in 2002–03.