The 30-year-old agreed new terms with the side he first joined in 2011 over the summer and boss Neil Lennon has elected to name Pratley his on-field chief.
Former skipper Matt Mills left to join Dougie Freedman’s Nottingham Forest earlier this summer and while midfielder Jay Spearing, who held the armband before, remains on Bolton’s books, he fell out of favour under Lennon and was jettisoned to Blackburn on loan last term.
“Darren will be our captain this season,” Lennon told the club’s official website.
“I think he’s the right age and he’s well respected in the dressing room by the players.
“He’s a consistent performer and he’s coming into his peak years. I think he’s ready for the responsibility.”
Bolton played their second pre-season friendly in Austria on Monday evening, going down 4-1 against Paderborn, with ex-Hull striker Nick Proschwitz on the scoresheet.
The Trotters have also had to alter their pre-season preparations once they get back to England.
They will now face Charlton at Macron Stadium on Friday, July 31, rather than Chievo Verona, because the Italian side, who were due to play the Addicks too, reported logistical problems.