Steve Clarke’s high-flying side, though, did not have it all their own way and would have been very happy to see substitute Chris Burke notch their second goal with 12 minutes remaining to secure their passage into the fifth round draw.
Kilmarnock defender Stuart Findlay opened the scoring after 19 minutes with a stunning volley from just inside the box, but Forfar had their moments as they chased an equaliser with Jamie Bain going close.
However, the top-flight side held firm and got the job done. The win was sealed with fellow sub Mikael Ndjoli played a ball across the face of goal and Burke slid in to score.
Kilmarnock manager Steve Clarke had told they fans they would be booing him if they jeered Jordan Jones after the winger signed a pre-contract with Rangers.
Jones had angered fans when he tweeted that the move was a “dream come true” and used the hashtag “WATP” – an abbreviation of the Rangers slogan “We are the people” – but the fans took the manager’s words on board as there was no booing to be heard from the stands.