Wanderers took the lead through Craig Dawson's fifth-minute header and then held firm to secure three points which moves them up to 10th in the Championship table.
"For me the signs were there that the training ground work we do day-in, day-out is paying off," said Freedman.
"Apart from the first 15-20 minutes it wasn't our most fantastic display on the ball, but off the ball, to a man, we worked very hard and made it difficult for Peterborough to have any clear-cut chances.
"Our defensive display has got to be talked about because we were asked a lot of questions."
The only sour note for Bolton was a first-half injury to Mark Davies, who has only recently returned from shoulder surgery.
"It has been a massive blow for us to miss Mark for the last three months. He twisted his knee and we'll see in the morning," added Freedman. "He's got a scan so let's keep our fingers crossed."
Freedman also explained the absence from his squad of Chris Eagles and Tyrone Mears.
"Eagles is not well. He phoned in on Monday, and Tyrone Mears has a blood infection so the two of them had to miss tonight," said the Scot.