The Dolphins added depth at the position with the offseason acquisition of veteran Brent Grimes and draft picks Jamar Taylor and Will Davis. Grimes is expected to start, and Davis has been impressive in practice this summer.
Returning cornerback Dimitri Patterson, in his eighth season, is also contending for a starting job.
Marshall had indicated via Twitter on Tuesday that he had been cut, although no official announcement had been made at that time.
I had a great time playing for the dolphins appreciate all the love from the fans but its time to move on
— Richard Marshall (@TheMarshall31) August 21, 2013
Pro Football Talk reported that the Dolphins attempted to trade Marshall, who signed a three-year contract with the Dolphins in 2012.
Marshall, 28, started four games for Miami last year but spent the final two months of the season on injured reserve with a back injury. The eighth-year pro, who has also played for Carolina and Arizona, had been scheduled to make $1.2 million this season.
Information from ESPN NFL Insider Adam Schefter and The Associated Press was used in this report.