Neill Collins has had his Blades contract terminated by mutual consent, to enable him to further his career in the United States.
An opportunity has arisen for the Scot to join North American Soccer League outfit Tampa Bay Rowdies and United have released the defender from the remaining months of his current deal, which was set to expire in the summer, to help facilitate the switch.
Collins has spent over five years at Bramall Lane, having joined from Leeds United in January 2011, and has amassed over 200 starts as a Blade, scoring 14 times in the process.
Manager Nigel Adkins thanked the defender for his efforts, commenting: "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."
Recognised as the division below Major League Soccer, the North American Soccer League season starts in April, hence the timing of the switch. The 32-year-old won't be the first Scottish Blade to have represented the Rowdies, winger Stewart Scullion enjoyed a spell in the US during the mid 1970s.
Of the move and his time with the Blades, Collins added: "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."