NFL Network Insider Ian Rapoport reported Saturday the Dolphins signed McDonald to a four-year contract worth $24 million, according to a source informed of the deal. The deal includes $10 million guaranteed, the largest ever for a player on a multi-game suspension, per Rapoport.
ESPN's James Walker first reported the pact.
McDonald is suspended for the first eight games of the season for violating the NFL's substance abuse policy.
The Dolphins initially signed the 26-year-old to a one-year, $1.34 million contract in March, after the suspension was announced.
The organization has been impressed enough with the suspended player to give him a new deal weeks before he played a regular-season down for the club.
The hard-hitting safety started 53 games for the Rams over four seasons. The 2013 third-round pick compiled 285 tackles, five sacks, four interceptions and 17 passes defended.