Inter chiefs are thought to have struck an 8million euro loan fee with the Blues, with Lukaku understood to have taken a pay cut to leave Stamford Bridge.
The Belgium striker only joined Chelsea in a club-record £98million deal last summer, but a number of controversies strained relations with the Blues.
Chelsea’s new co-owner Todd Boehly has put an immediate stamp on his tenure by giving the green light for Lukaku’s return to Inter.
US magnate Boehly has backed manager Thomas Tuchel over the decision to let Lukaku return to Italy.
And once the 29-year-old’s Inter return is officially complete, the Blues will be able to turn attentions to wider transfer business.
Chelsea will set about seeking a replacement, with the club understood to remain keen on Robert Lewandowski despite the Poland hitman’s desire to swap Bayern Munich for Barcelona.
Catalan giants Barcelona’s continued financial issues could yet open the door for Chelsea to pounce on Lewandowski’s unsettled situation.
Lukaku’s impending departure could yet point manager Tuchel towards a more fluid approach without a clear focal-point striker.
Chelsea hold strong interest in Manchester City’s Raheem Sterling, with the England forward open to leaving the Etihad Stadium with just one year left on his contract.
Chelsea’s next order of business after settling the Lukaku situation could well be to complete the long-mooted transfer of Sevilla’s Jules Kounde.
The France defender has made it clear for some months now that he is ready for the Stamford Bridge switch, but the two clubs will need to thrash out a fee.
Lukaku might have ended this season as Chelsea’s top scorer with 15 goals, but the vastly-experienced Belgium striker failed to live up to top billing.
A disastrous interview with Italian TV in December led to an apology to both Chelsea and the club’s fans in early January, after he had revealed his unhappiness in west London.
Despite several glimpses of hitting top form that never materialised, a move away now appears to suit all parties.
Lukaku is thought to have pushed for the move back to Inter in the end, and new Chelsea supremo Boehly has opted to clear the air by granting that switch.