The former India batsman rescued the visitors after they lost three quick wickets to the second new ball this morning, having resumed at the overnight score of 166 for three.
Jadeja, with Sarandeep Singh, pulled Delhi out of a tight corner after they were reduced to 225 for 6.
The Delhi captain, who was unlucky to miss a well-deserved ton after batting for close to three and a half hours and hitting 12 fours and 2 sixes, put on 84 runs with Sarandeep Singh (30) for the seventh wicket.
Jadeja got out when he chased a wide ball and edged medium pacer Usman Malvi, Mumbai's most successful bowler with four wickets in his kitty, behind. In all he faced 141 balls.
Ashish Nehra used the long handle to good effect to strike some mighty blows in making an unbeaten 41 off 87 balls with 6 fours and a six to boost the Delhi total considerably after Jadeja's departure at 333.
Delhi were all out 44 minutes after tea and in the remaining time Mumbai made 32 for no loss in 12 overs.