Germany have qualified for their first Fed Cup final for 22 years by seeing off Australia in the last four.
"It's a really special moment for us," Kerber told reporters. "It was tough and I knew I had to play my best tennis to beat Sam because she is a Grand Slam champion.
"After the first set I was just thinking about playing for the team and I was fighting until the last point. I was a little bit nervous on the last points but now I'm just happy.
"After 1992 we are now in the final and it means a lot for Germany and it's an honour for all of us."
Germany will be joined by either the Czech Republic or Italy in the final.