The Tottenham superstar has failed to have a shot on target in the opening two Group D games and was substituted in both the win over Croatia and Friday's goalless draw with Scotland at the Wembley Stadium.
Many pundits and fans have posited that Kane should be given a breather when the Three Lions take on Czech Republic but Southgate has revealed the 27-year-old will start against Jaroslav Šilhavý’s men.
"You can assume that, yes, absolutely," Southgate replied when asked if Kane would keep his place.
"He is fundamental not only to the goals he scores but the build-up play and everything else he brings.
"I know there will be a lot of questions being asked about him at the moment but he has been through that 100 times before and I have answered that in this role several times in the past and he has come up with the goals that have won us the next games and I expect that to be the same moving forward."
The former Middlesbrough head coach also defended his decision to substitute Kane in England’s opening two matches.
"In one of the games we were already ahead and we needed energy to press and keep the lead, we didn't need an additional goal," he added.
"Harry, during the World Cup, we ended up with him playing a lot of football and we've felt the need to manage that load a little bit this time and we have got good options on the bench to bring people into the game.
"But he is our most important player, there is no doubt about that, you've only got to look at his goalscoring record with us to see his importance to the team."
