Blake Shelton, Kelly Clarkson( inset) Blake Shelton, Kelly Clarkson( inset)

Blake Shelton will pull double duty at Kelly Clarkson's wedding to Brandon Blackstock. Not only will The Voice coach perform, but he will officiate the ceremony as well.

"He's not only singing; he's marrying us," Clarkson told Entertainment Tonight at Sunday's 48th Academy of Country Music Awards. "He totally is. He's done it before with people."

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Clarkson and Blackstock, who is Reba McEntire

's stepson and Shelton's manager, have been dating since late 2011. The couple announced their engagement via Twitter in December, something Shelton claims to have had a hand in."I told Brandon, 'Man, you need to grow up and you figure out that you need to marry this girl,'" he told Hollyscoop shortly after Clarkson shared the good news. "I am going on the record saying, 'I will do the music at the wedding or whatever you want to do. I'll be that guy. I will play for four hours if I have to, 'cause you need to get you head out of your a-- and ask that girl to marry you.'"Clarkson says she has already picked out her wedding dress, but they're having a hard time settling on a date due to everyone's hectic schedules.