The former Tottenham midfielder has become an investor and co-owner in the Swans.
Modric told the club's website on Monday: "This is an exciting opportunity. Swansea has a strong identity, an incredible fanbase and the ambition to compete at the highest level.
"Playing at the highest level, I believe I can provide my experience to the club. My goal is to support the club's growth in a positive way and to help to build an exciting future."
Swansea's owners are Andy Coleman, Brett Cravatt, Nigel Morris and Jason Cohen, who took over majority ownership from Jason Levien and Steve Kaplan last November.
Swansea chief executive Tom Gorringe declared: "I am excited that Luka has come on board as an investor and co-owner," He went on to laud the footballer as an exemplary figure in the sport: "There is no better role model in the game for our players, from the academy right through to the first team."
"His endorsement of our ambition and willingness to support us on our journey will be instrumental as we aim to continue to improve our results on and off the pitch."
He added: "In our conversations, he has demonstrated his passion for the club, his knowledge of how we are performing, and a genuine passion to help us improve. I am really looking forward to working with him more closely to drive us forward."