Rob Feinstein of RFVideo.com has posted the following on his Facebook page:

I was just informed Sting has signed a deal with WWE in the last 24 hours. I still think personally he will show up after Mania since it seems like Undertaker vs Brock is what they are aiming for. Reminds me when everyone thought Brock would debut in Miami but they waited for Raw.

This news comes about 24 hours after Anthony DiMoro of Sportsrant.com reported WWE and Sting reached some type of an agreement, and you can check out that report at this link.