Parkinson has guided the Bantams to their remarkable Capital One Cup final appearance against Swansea at Wembley tomorrow afternoon.
Parkin has been there every step of the way after he was recruited by Parkinson to become his assistant in September 2011.
And he has no doubts Parkinson - who first came to prominence at Colchester and, following a disappointingly short spell at Hull, had a decent couple of years at Charlton before results turned against him - has a fine career ahead.
"The job he did at Charlton was remarkable," said Parkin.
"They were on the slide financially after coming out of the Premier League and he got them into the play-offs, which was no mean feat.
"To go to Bradford and do what he has done highlights that over a consistent period of time he has been a very good manager.
"He has been linked with jobs and everyone is well aware he turned the Blackpool job down.
"What will happen after the final is entirely down to him. But I have been doing this a long time now and worked with some good managers.
"As far as I am concerned, he has all the credentials to be a top manager and I have no doubt that is his aim."
At 47, Parkin is two years older than Parkinson, but their paths to Bradford have been very similar.
Whilst Parkinson was building his reputation at Colchester, Parkin was doing much the same at Rochdale.
And, as with Parkinson and Hull, when Parkin made the step up to Championship level at Barnsley, he found it tough going.
At no point for either man, though, has there been anything like the cup run Bradford have been on this season, which accounted for Wigan and Arsenal before their resilience proved too much for Aston Villa over two games.
So now, after finding their entire Football League existence threatened last year, Bradford are looking forward to their first cup final appearance for a century, are one more win away from a place in the Europa League and, most importantly, back on a sensible financial footing again after the profligacy of those Premier League years.
"Bradford are one of many clubs who were on the crest of the wave in the Premier League and then slumped," said Parkin.
"It is very obvious the financial gains you do get in the Premier League can be more of a hindrance than a help.
"The fall from grace was quite dramatic and now we find ourselves in the lower tier."
Yet Parkin is wary of describing Bradford as a fallen giant.
If they were that, he argued, Parkinson would not be reduced to using school pitches - albeit pretty good ones - for training sessions in addition to the single council pitch available to them.
"It is easy to say Bradford is a big club," he said.
"The stadium and number of fans is outstanding. The support we have had this season is truly remarkable.
"But we have to use a private school for our training pitches because, unlike many clubs who have five or six at their disposal, we have one council pitch.
"The infrastructure in that sense is certainly not in place to build and be successful.
"I am sure that is something the club will have to look at in the near future."