The legendary musician has given producers permission to use his material in the 1960s drama, including his latest album Kisses on the Bottom.
The deal has reportedly opened the door for a possible cameo appearance in the series as a nod to his huge influence on the '60s as one of The Beatles.
"It's perfect timing because his new music suits the programme perfectly," a source told The Sun. "Action in the show has now reached the Swinging '60s. So it's only right that the man who was pivotal to the era is now involved in the show.
"Macca could have a walk-on part if he wished but it's unlikely that he'll ask for a role. He's more than happy just to supply the tunes."
Sir Paul McCartney became the final Beatle to be awarded a star on the Hollywood Walk of Fame this week.
Mad Men will return for a fifth season on March 25 on AMC, and in the UK on March 27 on Sky Atlantic at 9pm.
Watch a Kisses on the Bottom promo below: