The right-back, who signed a two-year deal at Portman Road in August, has made five appearances for his parent club this term.
However, the the 18-year-old will now spend the next few weeks at the Broadfield Stadium.
"He's athletic and aggressive and I think he will adapt well to the rigours of League Two. We'd like to thank Ipswich for letting us have Josh."
Emmanuel is expected to be in the Crawley squad for Saturday's trip to Carlisle United.