"I've matured as a player so the prospect of being captain isn't as daunting as it might have been a couple of years ago," Agbonlahor told the club's official website.
"I'm willing to do the job for as long as required, although as far as I'm concerned there's only one captain of this club.
"I am honoured to be wearing the captain's armband and I just wish it could have been in different circumstances. My biggest wish is that Stiliyan will come back and lead us again."
The 25-year-old will lead his side out against Premier League leaders Manchester United at Old Trafford on Sunday.