Foord scored the Gunners' third in a dramatic 3-2 win over Brazil's Corinthians to seal the FIFA Women's Champions Cup final.
Fellow Matildas Steph Catley and Kyra Cooney-Cross were also celebrating as Arsenal lifted the trophy at their own Emirates Stadium in north London.
The three become the first Australians to be crowned soccer world champions.
While Foord played her starring role off the bench Catley played the full 120 minutes of a gripping final in which the South American champions twice levelled, with the second equaliser coming from a last-gasp penalty to force extra time.
Cooney-Cross, still returning to full fitness after a period of compassionate leave in Australia to be with her cancer-stricken mother, was an unused substitute.
She did play in Arsenal's successful UEFA Champions League campaign, which earned them their place in this competition.
The Gunners, who beat African champions AS FAR, the team of the Moroccan military, 6-0 in Wednesday's semi-final, controlled possession for much of the match.
But Corinthians, who beat US champs FC Gotham in their semi, were roared on by a large contingent of fans who brought the passion of Sao Paulo to the rain-drenched English capital.
Arsenal opened the scoring after 14 minutes through Canadian striker Olivia Smith, who followed up after Lele had saved a Stina Blackstenius shot.
But seven minutes later Corinthians stunned their hosts. After Duda Sampaio had a drive tipped over the bar 40-year-old veteran Gabi Zanotti headed in from the resultant corner, skimming in off an unfortunate Catley.
As Arsenal pressed Lele made a string of saves but was finally beaten by Lotte Wubben-Moy's 59th-minute header.
Foord thought she had settled it with a 75th-minute shot but a defender's desperate lunge turned it against the bar.
Instead Vic Albuquerque scored a last-gasp penalty awarded on a VAR review to force extra time.
But Foord would not be denied her moment. Late in the first period of extra time Frida Maanum stole midfield possession and Arsenal broke. Foord stayed onside, received the Norwegian's pass, and drove her shot inside Lele's near post.Â
"We showed incredible character and resilience to come back in extra time," said Arsenal captain Kim Little.
"These things happen in football. You have to bounce back. When we came out in extra time we showed that, we created chances, and Caitlin (Foord) scored a great goal."
The only previous Australian to attain soccer world champion status is Mark Bosnich, who kept goal for Manchester United when they won the Intercontinental Cup, an annual competition between the European and South American champions, in 1999.
However, that event was not recognised by FIFA at the time and only featured clubs from two continents. In 2016 the world governing body retrospectively designated the winners world champions.
The new competition features the six continental champions and will run annually, except in years involving the quadrennial 16-club Women's Club World Cup, which is due to launch in 2028.
Australian champions Melbourne City, who were a penalty shootout loss from qualifying for this event via last year's Asian Champions League, are at the quarter-final stage of this season's ACL.
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