Chelsea were not able to convince Everton to sell defender John Stones despite making four bids for the 21-year-old, but the Blues did not walk away completely empty-handed from the transfer window.
Senegalese international Djilobodji, 26, joined the Blues on deadline day from Ligue 1 club Nantes.
Meanwhile, Hector will remain with Reading on loan after making a £4m move to Stamford Bridge.
It remains to be seen how much of an impact the new defenders will make, but Blues manager Jose Mourinho has been keen to add defensive depth all summer.
The Blues have struggled at the back so far this season, as they have conceded six goals in four games – three of these came against Manchester City in a devastating loss.
Here is a picture of Djilobodji holding his new Chelsea kit for the first time.