Johnson, currently a senior at New Braunfels High School, helped make the incoming freshman class the largest signing class since the 2001 signees, the current junior class for the Tide.
She was named to the 2002 Greater All-San Antonio team as a catcher and was also named All-District in 2003 and 2002.
"Katie has tremendous potential," said Alabama Head Coach Patrick Murphy. "Every time we saw her play she hit the ball hard. She's very versatile, a great athlete and comes from a very athletic family."
Johnson's father, Rob, played football for the University of Texas while her grandfather played football at Southern Methodist University.
Johnson will join Chrissy Owens, Jordan Praytor, Lauren Roark and Dani Woods as the Tide's freshman class for the 2005 season.