Shelton surprised the singer on Sunday with a platinum diamond ring after phoning Lambert's father to ask for his blessing, reports E! Online.
"That was so Southern and old-school and perfect," said Lambert.
"Weddings are great and engagements are great and diamonds are especially great. But I'm just excited to be married because I want to tell Blake I really can love him the rest of my life and be happy and make him happy."
The engagement came only hours after both Shelton and Lambert were announced as nominees for this year's Country Music Awards.
The pair began dating in 2006.