The Wearsider has agreed to join the Bees as a free agent following his release from Ajax earlier this week.
Sunderland had been heavily linked with a potential move for the 35-year-old, who made 79 appearances for the [Black Cats](http://www.thenorthernecho.co.uk/sport/football/sunderland) at the start of his career after progressing through the academy set-up at the Stadium of Light.
Sunderland’s recruitment team were aware of Henderson’s likely availability at the start of the summer, and have been monitoring his situation throughout the last couple of months.
**READ MORE**:
However, with Habib Diarra and Noah Sadiki already having been recruited to strengthen the central-midfield ranks, the Black Cats hierarchy decided against offering Henderson what would have been an emotional return to his hometown.
The presence of Dan Neil and Chris Rigg in Sunderland’s midfield mix was also a factor, with Sunderland officials not wanting to hamper the development of two of their most promising young players.
Sunderland's sporting director, Kristjaan Speakman, was aware of the emotional pull behind bringing Henderson back to the Stadium of Light, and the veteran midfielder's experience and leadership qualities would potentially have offered something in a squad that, on the whole, remains extremely young.
However, senior sources claim there was a determination to ensure 'heart did not rule head', with Speakman having been involved in the unsuccessful decision to offer Jermain Defoe a second spell as a Sunderland player.
In the end, it was decided that Sunderland should look to the future rather than the past, hence the move for alternative, much younger central-midfield targets.
Henderson was made aware of his boyhood club's decision, and having turned down a series of alternative offers including a firm approach from Porto, the North-Easterner has opted to join Brentford, who finished in tenth position in the Premier League next season.
The England international will hope that remaining in the English top-flight will enhance his chances of being part of Thomas Tuchel’s squad for next summer’s World Cup finals in North America.
Sunderland, meanwhile, are in pre-season action for the first time tomorrow when they play games against both Gateshead and South Shields.
A development side will take on Gateshead at Hebburn Sports & Social Club, before Regis Le Bris’ first team line up against South Shields at Mariners Park.