Iro, 28, has made five appearances for the Bees, scoring a 97th-minute equaliser to earn Edgar Davids' side a 2-2 draw with Exeter just before the turn of the year.
He told Barnet's official website: "I am very happy to have extended my loan because I want to be playing first-team football and I have had the opportunity to do that here.
"We have been on a very good run which will hopefully continue on Saturday against Rotherham."
Iro joined Stevenage in September having played the majority of his career in the USA, attending the University of California before being drafted to the Columbus Crewe.
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