The 38-year-old Hollywood star - who has been friends with the 36-year-old TV personality since they studied together at Manchester University - invited Rinder to be one of three friends by his side at his ultra-private wedding to Sophie Hunter on the Isle of White on Valentine's Day (14.02.15), despite previous speculation Tom Hiddleston had filled the role.
A source explained: ''Benedict had three best men, but only one was famous - and that was Judge Rinder.
''There was speculation that he chose another actor, but he wanted genuine old friends in the role.''
The 'Imitation Game' was ordained on the internet in order to officiate Rinder's wedding in Ibiza to his partner Seth Cumming in 2013, but the pair try to keep their friendship private.
A source told The Sun newspaper: ''They keep it pretty quiet. They were friends before either found fame.''
Rinder has previously said he's hugely appreciative of the support he's received from his long-time friend.
Speaking last year, he shared: ''He's an old friend from Manchester university. He's always been hugely supportive.''
Cumberbatch, meanwhile, said officiating his friend's wedding might be the start of a new career for him.
He joked: ''Next it'll be children's parties and Bar Mitzvahs!''
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