John Marquis has completed a transfer to fellow League One side Lincoln on undisclosed terms.
The striker brings to an end his two-and-a-half-year stay on the south coast, having arrived from Doncaster in the summer of 2019.
He netted 38 goals in 127 appearances for Pompey, which includes a brief loan spell on the south coast in 2013.
Blues boss Danny Cowley said: “John has been an excellent professional for the entire time we’ve worked with him and constantly strives to improve his own game.
“He always tries to do his best for the team and there’s nobody who wanted this spell to work more than him.
"John has been an excellent professional for the entire time we’ve worked with him and constantly strives to improve his own game."
“I know that he can be content that he gave everything he could in order to be successful at Pompey.
“Having spoken with John throughout this month, though, it became clear that we needed to let him move on. It was the right time for everyone involved.
“He has an outstanding attitude and work ethic, so I have absolutely no doubt that he will go on and enjoy more success in his career.”
Marquis had struck four times for Pompey in 24 games this term, bagging a brace in the 4-0 home victory over Sunderland and also netting in Fratton successes over Crewe and Bolton.
Lincoln currently sit 18th in the League One standings and will visit the south coast to face the Blues at Easter.