Having admired his performances for Swindon in League One last season, Boothroyd believes the former Leeds United trainee can make an impact at the higher level.
"Danny is a fantastic signing for us," he said. "There was a lot of interest from other clubs in this division, so it's a testament to the set-up here that he opted to join us.
"He adds another option to the squad and the potential to get goals, so I am looking forward to working with him.
"Everyone saw what he was capable of in his loan spell with Swindon last season and he will only get better. We will get the benefit of that development, while he will benefit from being here."