He said the level of interest the Blues boss showed in him proved decisive after he penned a three-year deal at Fratton Park.
The former Luton midfielder completed his move to Pompey for an undisclosed fee late on Monday night – providing the perfect end to a dramatic day.
At one point Ipswich looked set to hijack a deal which Cowley had been working tirelessly on to complete.
However, Morrell decided against a move to Paul Cook’s big spenders, instead favouring a reunion with his former Lincoln manager.
It’s a decision that has gone down well with the Fratton faithful, who were fearful of further Blues frustration in the transfer market.
Morrell confessed playing in front of those Pompey fans was a huge draw, too.
But he said his relationship with Cowley – someone he’s been in regular contact with since their Imps days during the 2019-20 season – was a massive reason why he committed his future to the Blues.
Asked by the club’s media team what convinced him to move to the south coast, the Wales international said: ‘I think, as always when you join a football club, it’s a combination of everything.
‘The fan base is a massive factor in that, it's something that means a lot to me.
‘Football is (meant to be) played in front of a passionate fan base and big crowds, and that's certainly the case here.
‘(It’s) a club that's achieved a lot in football and has ambitions to get back to where it has been.
‘And, obviously, the gaffer’s a massive part in that as well - someone who I've always had a great relationship with.
‘I worked with him at Lincoln, fairly shortly, but we've always kept in pretty close contact and, like I said, I've always had a good relationship with him.
‘And to be honest, I've probably spoke to him in the last couple of months as much as my parents.
‘So just to have that interest in you means a lot and in the end it's a massive factor in why I'm sat here today.’
The News revealed Pompey’s interest in Morrell at the start of June, which gives an indication of the length of time Cowley has invested in his 12th signing of the summer.
It was initially reported that the 19-times capped Wales midfielder’s preference was to remain in the Championship.
But it was acknowledged that if he was to move to League One then the Blues were his favoured destination.
The Ipswich-born ace backed up that understanding as he accepted Cowley’s offer.
Yet it’s not a division Morrell intends to stick around in as he targets promotion alongside his new team-mates.
Nor does he see his latest move as a ‘step down’.
Morrell added: ‘It's a league I played in a couple of years ago and I think you just have to look at the strength of the division this year, I don't see a massive difference in League One and the Championship.
‘At the end of the day for me, playing football on a regular basis is the most important thing regardless of the level.
‘I don’t really see it as a step down coming to Pompey, to be honest.
‘It's just something I'm really, really excited for.
‘Like I said, the opportunity to play for a club like this was something that was too good to turn down really and playing regular football is the main thing for me.
‘It is in League One, but I don't see myself as settling to be a League One player for the rest of my career.
‘I still have ambitions to play in the Championship, but I think doing it with Pompey would be much sweeter.'