The 31-year-old passed a medical at Chelsea’s Cobham training ground yesterday morning and signed an 18-month-deal, with an option for a further year.
Meanwhile Manchester City pulled out of a deadline day deal for Riyad Mahrez after Leicester valued him at an eye-watering £95m – £30m more than they were prepared to pay.
And Tottenham completed the £25 million capture of Paris St-Germain winger Lucas Moura.
The capture of Giroud, who played for Arsenal as sub at Swansea on Tuesday, will satisfy Chelsea manager Antonio Conte’s desire for a striker to provide competition for Spaniard Alvaro Morata.
The Stamford Bridge club had also made inquiries for Roma’s Edin Dzeko, West Ham’s Andy Carroll and Stoke veteran Peter Crouch, as well as Tottenham’s Fernando Llorente, before settling on Giroud who scored 105 goals in 253 games for the Gunners.
Aubameyang, 28, now hopes to emulate the achievements of his hero Thierry Henry following his £55 million club record arrival at the Emirates, on a day of good news for Gunners fans with Mesut Ozil signing a new three-and-a-half year contract.
“I think the club has such a big history and great players like Thierry,” he said. “He’s an example for us strikers.
“He was fast and scored a lot of goals. I think I have to work a lot to be like him, but I will do.”
But Arsenal missed out on West Brom defender Jonny Evans, although they did enquire about him yesterday, on a day where they allowed Mathieu Debuchy to join French side St Etienne.
Manchester City are understood to have offered a package of £55m cash plus Eliaquim Mangala, who was valued at £10m, for Mahrez but that was rejected by the Foxes.
Mangala eventually joined Everton on loan for the rest of the season with the Mersesyide club picking up the defender’s £100,00-a-week wages.
Leicester wanted a package worth £95m – either all money or cash plus a player – for the Mahrez, 26, who was the PFA Player of the Year in 2016 but Pep Guardiola’s men walked away.
But the breakdown leaves Mahrez in a difficult situation for the second time this season after a move in August failed to materialise. Mahrez was left out of the squad for Leicester’s trip to Everton last night.
Another Leicester player Islam Slimani arrived on Newcastle owner Mike Ashley’s private jet ahead of a planned loan deal until the end of the season.
Spurs are notoriously wary of signing players in January but the arrival of Brazilian Moura offers excitement, not least because he is the club’s fifth most expensive signing.
Moura, 25, joined PSG for £33.5 million in 2013 and scored 46 and made 50 in 229 appearances for the French side.
Everton winger Ademola Lookman has completed a loan move to RB Leipzig until the end of the season.
Swansea have bought back Andre Ayew in an £18 million deadline day deal from West Ham that will reunite him with his brother Jordan.
The last time the Ghanaian internationals played together was for Marseille in France, when they combined to win both the Ligue 1 title and the French Cup. Now their task will be to join forces to keep the Swans in the Premier League.
Watford brought in Didier Ndong on loan from Sunderland while allowed Isaac Success to end his unsuccessful time at Vicarage Road and move on loan to Malaga.
Leeds have signed striker West Brom Tyler Roberts for £2.5 million while Derby striker Chris Martin joined Reading on loan.