Maxwell, who signed a one-year, $3 million deal with Seattle this offseason, had been projected as the Seahawks' starting left cornerback.
By being placed on IR on Saturday, Maxwell is ineligible to be activated off the list later in the season. However, he could play again this season for Seattle, or another team, if he reaches an injury settlement with the Seahawks.
Released by the Miami Dolphins in October after losing his starting job, Maxwell returned to the Seahawks in November after Richard Sherman suffered a season-ending Achilles injury. He played the majority of his first game back after rookie right cornerback Shaquill Griffin suffered a concussion on the opening possession, and Maxwell remained in the starting lineup for the final six games, eventually replacing Jeremy Lane on the left side.
A sixth-round pick by Seattle in 2011, Maxwell started 17 games between the 2013 and 2014 seasons before signing a lucrative free-agent deal in 2015 with the Philadelphia Eagles, who then traded him to Miami after one season.
Also Saturday, the Seahawks placed tight end Ed Dickson on the non-football injury list. Dickson never participated in training camp, and he had a setback in his recovery from muscle injuries to his quadriceps and groin.
ESPN's Brady Henderson and The Associated Press contributed to this report.