Pompey have signed versatile midfielder Tom Naylor on a three-year deal.
The 26-year-old – who is also comfortable in defence – will officially become a Blues player on July 1 when his contract expires at Burton.
Blues boss Kenny Jackett said: “It strengthens the spine of our side, while he also brings us recent Championship experience.
“Tom’s a ball-winner and I feel that he’ll complement the other talented players we already have at this club.
“He’s someone who can play in a variety of positions, although he’s primarily been brought in as a defensive midfielder.
“We do feel that the squad is being improved this summer and we’re getting to where we want to be.”
Naylor joined Burton in the summer of 2015 following a spell on loan and made a total of 134 appearances for the Brewers, scoring 13 goals.
He began his career at Mansfield and has also turned out for Derby, as well as having temporary stints with Bradford, Grimsby, Newport and Cambridge.
Loan : Burton Albion – Portsmouth
Pompey have signed Damien McCrory on loan from Burton until January.
The 27-year-old Irishman is primarily a left-back, but can also be utilised in a more advanced position.
Blues boss Kenny Jackett said: “He’s an experienced player who provides competition for Brandon Haunstrup in that role.
“It’s a specialist position and we’ve been looking to bring someone in since Tareiq Holmes-Dennis’ unfortunate injury on the opening day.
“He’s won promotion from this division before and has also played in the Championship, so we’re delighted to bring him in on loan.”
McCrory started his career at Plymouth and enjoyed a successful stint with Dagenham before joining Burton in 2012.
He has made almost 200 appearances for the Brewers and represented Republic of Ireland at youth level.
Striker completes Fratton switch
I’ve played against Pompey a few times and I’ve always been struck by how fantastic the fans have been”
Pompey have signed striker Adam McGurk on a two-year deal.
The 26-year-old was available following the expiration of his Burton Albion contract.
He scored seven goals in 41 appearances last term – including one against Pompey – to help the Brewers lift the League Two title.
And McGurk revealed that it was not a difficult decision to move to Fratton Park.
He said: “What attracted me was the size of the club and the large crowds that come to watch the games.
“I’ve played against Pompey a few times and I’ve always been struck by how fantastic the fans have been, despite a difficult few years.
“They stick with their side, even when they’re not winning. That’s always impressed me and my team-mates.
“I’ve also played against Paul Cook’s Chesterfield sides before. I liked the way they approach the game and also how much they wanted to play for him.
“When I sat down to talk to him, I could see how much passion he has and wanted to be a part of that.
“I’m excited for the new season. It’s been a stressful few days getting the deal done, but now I’m looking forward to getting down to work and bonding with my new team-mates.”
McGurk has echoed his new manager and fellow summer signings by targeting promotion.
He said: “I think that everyone expected Pompey to do better over the past few years.
“This club belongs in a higher division and now we have to make sure that happens, so we need to gel as quickly as possible.
“I’ll offer hard work and creativity to the side. Hopefully I can score more goals than last season, although the important thing is that I’m able to contribute to a winning team.”
McGurk – who has represented Northern Ireland at under-21 level – played youth team football for Aston Villa before moving on to Hednesford and Tranmere.
He signed for Burton in the summer of 2013 and netted 19 goals in 83 games during his two years at the Pirelli Stadium.