The Basque outfit recorded a 1-0 win over Deportivo Alaves at the weekend, with that result meaning that they now hold an unassailable seven-point advantage over the teams outside of the top two automatic promotion places in the Segunda Division.
"It's a historic day. I missed the train as a player nine years ago and since then I've had this thorn in my side," Inside Spanish Football quotes Garitano as saying.
"I've dreamt a lot about this moment, I've been waiting for this say and it's come true.
"We did it with the team in the dressing room; we did it as a team, suffering until the end with 10 players. I can't wait to see the look of joy on the faces of the older fans."
Eibar have secured back-to-back promotions after joining the Segunda just last season.