Jagielka, 38, and Rodwell, whose deals were due to expire on 30 June, signed short-term extensions to take them to the end of the delayed 2019-20 season.
“Phil is a valuable and respected member of the squad,” said manager Chris Wilder. “The same applies to Jack, who offered us versatility and gave us options within the group during the second half of the last term.”
England international Jagielka made 10 appearances after rejoining United on a free transfer at the beginning of last season following 12 years at Everton.
Rodwell played two games after arriving on a free transfer in January.