Nicolas Jackson's early opener had given Mauricio Pochettino's men the lead but Almirón's leveller in the first half's dying moments at the Mercedes-Benz Stadium - where he starred for Atlanta United before his move to Tyneside - ensured Eddie Howe's men maintained their unbeaten pre-season record as preparations continue for the new campaign.
United look bright early on, with Anthony Gordon's direct running causing problems, but they fell behind after 12 minutes. It was a simple enough finish for Jackson after Ian Maatsen's neat through ball found him in space, and the summer arrival from Villareal prodded beyond Martin Dúbravka to open the scoring.
Chelsea's pace in attack posed a few questions for the Magpies' backline, with Jackson and Christopher Nkunku particularly prominent. Another quick burst led to Cesare Casadei's snapshot flashing just wide before Maatsen tested Dúbravka after a solo run down the left from Mykhailo Mudryk.
Newcastle - with teenager Lewis Miley impressing in midfield on his first non-competitive start - were forced into a first half change when Fabian Schär went off injured. His replacement, Alex Murphy, almost produced a leveller when his header from Alexander Isak's knock-down was instinctively repelled by Kepa Arrizabalaga.
In stoppage time at the end of the half, though, they did find an equaliser. It came from Almirón, who latched on to Gordon's pass and accelerated beyond the Blues' defence before placing a low left-footed shot beyond the reach of Kepa - much to the delight of the local contingent, who had idolised the Paraguayan during his spell with Atlanta between 2016 and 2019.
At the break, Nick Pope entered the fray for his first appearance of pre-season after recovering from injury, but chances for Howe's men remained at a premium. One fell to 17-year-old Miley, but his effort from Isak's cutback lacked the requisite power and direction, making it easy for Kepa to hold. At the other end, Pope tipped away a low Nkunku drive as the contest opened up a little.
Just after the hour, England stopper Pope pulled off an even better stop to deny his international teammate Conor Gallagher, whose powerful strike looked destined for the bottom right-hand corner until the Magpies' goalkeeper's intervention. His contributions proved to be significant; another fine save to turn away Ben Chilwell's drive in stoppage time helped ensure United would remain unbeaten in their preparations for the 2023/24 season.
Newcastle United: Martin Dúbravka (Nick Pope 46); Kieran Trippier (Harrison Ashby 85), Fabian Schär, Sven Botman, Dan Burn; Joelinton (Jay Turner-Cooke 85), Sandro Tonali, Lewis Miley; Miguel Almirón (Ben Parkinson 77), Alexander Isak, Anthony Gordon.
Substitutes: Mark Gillespie, Alex Murphy, Remi Savage.
