The contract includes $15 million guaranteed for Jones, who would have been an unrestricted free agent in 2014.
Jones, entering his fourth season out of Georgia, had four interceptions and 94 combined tackles last season.
Jones wrote a message of thanks on Twitter, without confirming the deal.
Just want 2 take this time 2 thank God for this blessing!! And thank the dolphins Organization, family,friends, and fans that be believed!
— Reshad Jones (@reshadjones9) August 6, 2013
Information from ESPN NFL Insider Adam Schefter was used in this report.