Associated Press sources report Starling will receive a signing bonus of $7.5-million over three years.
Starling attended summer classes in Lincoln and made an appearance on Husker Fan Day earlier this month, but decided not to participate in practice sessions with the football team.
Starling was the fifth overall pick in the Major League Amateur Draft in June.
Husker Head Coach Bo Pelini offered this: “Everyone associated with our football program at Nebraska wishes Bubba nothing but the best in his future with the Kansas City Royals organization. I know this decision has been very difficult for Bubba and his family, as it would be for anyone in his position. In the end, Bubba was in a win-win situation regardless of his choice, and we respect the decision he has made. I personally will root for Bubba in every game except when he plays against the Indians!”