Neill Collins has thanked Sheffield United's fans for their support during his time at Bramall Lane, adding: "Once a Blade, always a Blade."
The Scottish defender, who made over 200 appearances for the Bramall Lane club since joining from Leeds in 2011, has signed for American side Tampa Bay Rowdies.
Collins was out of contract in the summer, and United officials agreed to release him early to sign for Tampa - who are currently on a tour of England.
And the 32-year-old said: "These opportunities only come along once in a lifetime and it was the right move for me and my family at this point in my career, I am indebted to the club for allowing me to take up this opportunity.
"There have been some devastating lows but some fantastic highs during my time at Bramall Lane and there is no question that once a Blade always a Blade - this wonderful club has a way of getting under your skin.
"I'd like to thank the players and staff I had the pleasure of working alongside. There are so many fantastic people working behind the scenes that deserve to see the club back where it belongs along with the long suffering fans who are the most loyal in the country.
"Thank you for the memories and all the best in the future."
United manager Nigel Adkins added: "Over a number of years, Neill has given great service to the club and we wish him all the best with this next chapter in his career."
Florida-based Tampa were founded in 2008, and play in the North American Soccer League - one division below the star-studded MLS. Former American wonderkid Freddy Adu plays for them, and Collins' fellow Scot Stuart Campbell - formerly of Leicester, Grimsby and Bristol Rovers - is the club's head coach.
The 32-year-old defender celebrated making his 200th United appearance by scoring against Southend earlier this season, and said afterwards: "I’m a realist, I know I’m probably not going to get to 400 appearances here. But I’m just humbled to have made 200 for such a great club.
Everyone, hopefully, knows I’ve always given 100 per cent. It might not always have been to the quality some people think it should be or would like, but I’ve always given absolutely everything for this club."
Collins found himself frozen out under the reign of Nigel Clough, but returned to the side under his successor, Nigel Adkins. The former Scotland under-21 and B international also played twice for United in a loan spell from Sunderland in 2006.