Vaughan - the Premier League's youngest ever scorer - joined from Norwich for an undisclosed fee having spent last season on loan with the club and notching 14 goals.
And after his effort gave Huddersfield their first win of the season to leave Millwall still goalless and pointless this term, Robins was full of praise for his new front man.
He said: "He was the best loan signing the club's ever had and one of the all-time loan signings. That prompted us to the business we did this summer.
"We paid money for James, we paid money for Jonathan Hogg and apart from that it's been free transfers and they've good acquisitions so far.
"We're not getting carried away, it's still very early days. It's good to get the points on the board as it gives us confidence.
"It was a decent performance. We withstood everything Millwall threw at us and it's not an easy place to come. I think they're having a difficult time at the minute with a new manager who's trying to impose his ideas on the players.
"I think he's finding it difficult and he needs support. I think Steve (Lomas, Millwall's new manager) needs the fans help to get a bit of stability as they have a good squad of players and they play some decent stuff."
Robins' description of life for new Lions boss Lomas was very much on the money with the former St Johnstone manager finding life to date tough in south London with his men now rooted to the foot of the Championship.
But despite this latest setback, Lomas remains defiant.
He said: "I am enjoying my time here. I could've stayed up in Scotland and settled there. But I wanted to come here and test myself and this is a real test.
"I am enjoying it, as perverse as that may seem, but you have to take stock when things aren't going well. I thought we kept going right to the very end, it gives me heart that the lads are going every step of the way.
"I'm sure if we keep performing like we did today we'll get our rewards.
"I thought that's the best we've played this season. We had a good week's training and we started on the front foot with Huddersfield being camped in.
"Throughout the game we had eight decent chances and you have to convert one of them.
"But to concede a sloppy goal from a set-play is bitterly disappointing and that sort of us put us on the back foot."