Almiron, who helped Atlanta United win MLS Cup at the same stadium in 2018, found the bottom corner of the net with a left-footed finish to pull Newcastle level deep into first-half stoppage time. The more than 70,000 fans in attendance responded with a thunderous ovation.
Chelsea had taken the lead in the 12th minute when new signing Nicolas Jackson continued his impressive preseason form.
Fresh from scoring in a 4-3 win over Brighton on Saturday, the former Villarreal forward latched onto a through ball from Ian Maatsen and slipped the ball effortlessly past Martin Dúbravka in the Newcastle goal.
Newcastle, meanwhile, will take on Brighton in New Jersey on Friday before returning home for their final preseason matches ahead of the new Premier League season.