Guy Hedger, 61, was killed in the early hours of April 30 after intruders entered his £1million home in Castlewood.
Kevin Downton, 40, from Winterborne Stickland near Blandford, Dorset, was charged with murder and aggravated burglary on Friday, Dorset Police said.
He is due to appear at Poole Magistrates’ Court on Saturday.
Two other men, Jason Baccus, 41, and Scott Keeping, 44, both of Verney Close in Bournemouth, were charged with the same offences earlier on Friday and will also appear at the court on Saturday.
Detective Superintendent Kevin Connolly of Dorset Police said: “Following a fast moving and thorough investigation, we have consulted with the Crown Prosecution Service who authorised the charges.
“Family liaison officers have updated Guy’s family with this development and our thoughts are with them at this difficult time.”
A 40-year-old woman from Bournemouth who was also arrested in relation to the case has been released under investigation, the force added.
The alarm was raised at 3.03am on April 30 when police received a call reporting Mr Hedger had been shot with a shotgun.
The insurance executive was pronounced dead shortly after arriving at hospital. It is believed jewellery, including designer watches, was stolen.
Mr Hedger’s partner, Simon-Pierre Hedger-Cooper, 48, a voluntary sector worker, was also in the house at the time.
Earlier this week, Mr Hedger’s family paid tribute and said: “Guy was a caring and compassionate partner, son, brother and uncle who lived life to its full and enriched the lives of all those who knew him.
“Guy will be sorely missed by family, friends and colleagues, but he will live in our hearts forever.”
A cordon remains in place at the address while crime scene investigators examine the scene.
Mr Hedger was a director of the Avonbourne International Business and Enterprise Trust, which runs colleges and a primary school in the Bournemouth area.