Knott was due to head back to Wearside after Monday's 2-0 defeat at Southend but has now agreed to stay on until the end of the season.
"I was ready to go back to Sunderland after the game, but Wimbledon asked me to stay on Saturday and it is a bit of a relief," said the 19-year-old midfielder.
"That is really good for me and hopefully I can get four more games under my belt."
Knott is a doubt for Saturday's trip to Crawley after tweaking his hamstring.
But he added: "Hopefully, I will be back for this weekend, if not, then the week after."
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