Darby was a youth player for Liverpool. As a Liverpool squad player, he was loaned to Swindon Town, Notts County and Rochdale. He then signed for Bradford City, reaching the 2013 Football League Cup Final in his first season. He made 239 appearances for Bradford before signing for Bolton Wanderers in July 2017. Darby retired from professional football in September 2018 after being told he had motor neurone disease.