Flint, 28, has penned a four-year contract with the club and joins Paddy McNair as Tony Pulis continues to strengthen his squad ahead of the new season.

Once again, Boro beat off stiff competition to land a player who was a target for a number of clubs.

The towering centre-back has developed a reputation as one of the best defenders outside the top flight and boasts an imposing presence in both penalty areas.

Having joined Bristol City from Swindon Town in 2013, he was named in the League One Team of the Year in 2014/15 as the club won the Football League Trophy and promotion to the Championship.  

He was named The Robins’ Player of the Year the following two campaigns, while last season saw Flint score nine goals in 46 appearances as Lee Johnson’s side launched a surprise promotion push and reached the semi-finals of the Carabao Cup.

The defender, a threat at both ends of the pitch, will add further competition for places in the Boro squad.

Flint will travel with the squad to Austria for the club’s pre-season training camp.

Due to the terms of the deal, we are unable to disclose the fee.