Dumoulin covered the 31 kilometre time trial in 40 minutes and 52 seconds. Third before Stage 20, Primoz Roglic finished one minute and 12 seconds behind the flying Dutchman.
Froome now rebounds back on to the Paris podium, sandwiching Dumoulin between himself and Sky team mate Geraint Thomas.
The four-time Tour de France champion said he is proud of the Welshman.
"I didn't come here and I didn't win the Tour de France," he said. "But at the same time I've seen a good mate of mine who over the years who worked so hard for me.
"He's been there and thereabouts but to see him do it now makes me really proud at the same time.
"It's been emotional for all of us. We are human beings at the end of the day I think people forget that sometimes."
"It's been a great Tour and for us both to stand on the podium in Paris will be really special."
Froome also still believes the Giro-Tour double is possible, a feat not achieved since Marco Pantani in 1998.
"I should be third tomorrow, if nothing goes wrong. I still believe that it's possible but it's not going to be this year.
"Tom as well, for him to be second in both grand tours, I think it shows it is possible to do both of the races at a really high level, which only leads me to believe it is possible to do both of them."
For now though, Froome's thoughts turn to home.
"Huge relief! Just looking forward to getting home now got a little baby girl on the way anytime now.
"It's been emotional for all of us. We are human beings at the end of the day I think people forget that sometimes."
