The Norwegian, a double player of the season award winner last term, is poised to exit The Hawthorns after a little over 12 months at the club.
His move to the Serie A outfit is understood to be worth in the region of £10million, plus a sell-on clause.
It represents a huge profit on the deal that brought Heggem, 26, to The Hawthorns last summer for a fee of around £525,000 from IF Brommapojkarna in Sweden.
Heggem was a huge figure for the Baggies last season and featured in all but one Championship fixture. He went on to receive deserved club honours at the end of the season and became a regular for his nation.
Bologna’s interest has grown during the off-season and initial interest came at a bid of £6.5m but Albion were keen for a bigger fee.
The Norway international did not play a part in Tuesday night’s EFL Cup first round penalty defeat to Derby and is believed to be on his way to finalise the move in the Emilia-Romagna region. He was set to be involved but a late move saw the academy’s Alex Williams start and Harry Whitwell move on to the bench.
Critically, the incoming funds will be important for the club to reinvest to help head coach Ryan Mason complete his squad for the new season, as well as ensure the club remain compliant in profit and sustainability regulations.
Albion have signed three players this summer to the tune of fees around £7m – with two new central defenders already through the door in Nat Phillips and George Campbell.
But Albion’s spending was not limitless due to financial fair play laws as the club continue to recover under owners Bilkul in the post-Guochuan Lai era.
It remains to be seen if Mason and sporting director Andrew Nestor desire another replacement to cover for Heggem’s exit. Kyle Bartley retired from playing last week leaving just three options in Phillips, Campbell and Caleb Taylor.
The fee and significant profit recouped is seen as a big win in the club’s profit and sustainability model and will be key for replacements in the coming weeks prior to the September 1 deadline. As well as at centre-half, Albion are mulling options in the midfield department with just Alex Mowatt, Jayson Molumby and Ousmane Diakite as senior regulars.
Heggem’s sale will be the biggest fee received by the club since Matheus Pereira’s move to Al Hilal for £16m in 2021.