Ex-Cobblers skipper Goode joins Sheffield United on loan from Brentford
The 26-year-old skippered Northampton to play-off glory in 2020 before becoming the club's record sale when he joined Brentford for a seven-figure fee in the same summer.
The centre-back has made six appearances in the Premier League this season but drops back down to the Championship for the rest of the campaign.
Blades boss Paul Heckingbottom said: "We are delighted to bring in Charlie, he offers us good competition in an area of the pitch where we are a little light.
"He has good experience, including at the top level, and will be comfortable in a number of positions across the back line, whether we play with three or four at the back."
Phil Giles, Brentford director of football, added: “Charlie has done very well when he has come into the team this season and last.
"However, he has not got enough game-time in total in the last 18 months, so the best thing he can do is to try to get that elsewhere, ready to return to us in the summer and push on again next season.
"We wish him and Sheffield United well for the rest of the season.”