Pompey have announced four players will depart the club.
Nevertheless, Brandon Haunstrup and Alex Bass will pen new deals and talks are currently ongoing with Adam May to extend his Fratton Park stay.
Christian Oxlade-Chamberlain's contract could also be prolonged as he continues his rehabilitation from his broken leg.
Naismith's departure no doubt heads the list of those exiting PO4. He spearheaded Paul Cook's Pompey to the League Two title last season but hasn't displayed the same level of form in the third tier under Kenny Jackett.
On Facebook page Portsmouth FC - The News and on Twitter the Fratton faithful have been debating if Kenny Jackett has made the correct decisions.
Here's what they had to say...
Lorraine Wells via Facebook
Was hoping they would sort something out. I like him (Naismith) and in particular last season really got us over the line and that shouldn’t be forgotten. All the best to you Kal with your football and your baby!
Great League Two player, average at best in League One. I wish him well and think he will find his level lower down the English league or back in Scotland.
Naismith just had a bad season all players have it think we should of kept hold of him got rid of Adam May he's the one should be leaving not Kal.
He deserves all the credit for what he did for us last season but this season was no where near as productive and I don’t think anyone would disagree on that. I would suggest that if there was no agreement by both sides and without knowing the details then he did really want to ply his trade elsewhere. Good luck for the future
Dave Martin (@dave_martin12) via Twitter
Widdrington is a shame as he's got talent. Love Kabamba but we can't be sentimental he's not good enough.
Kal was different gravy at the end of last season and arguably is why we went up but he's been terrible in League One. No big loss. #pompey
Christie Walker (ChristieWalker4)
Karl Naismith - absolutely pivotal to the title win, scored vital goals at vital times. Battled his way back from the brink of being cast aside. Unfortunately just didn’t look at the races this season. Can only wish him well #Pompey
Andy Horton (@dumbohorton)
That 2nd half of our title winning season was just insane from Naismith. Thanks for the memories #Pompey