With 33 runners sent to post for the Heritage Handicap, the Mullins-trained 5-year-old came out on top from stablemate Uradel, after putting in a game effort under jockey Seamie Heffernan.
As the runners came in to the final half-mile of the Newmarket contest, Stars Over The Sea and Cliffs Of Dover who had led the 33 runners began to fade, providing eventual winner, Low Sun, with an excellent tow in to the race.
The son of Champs Elysees then got to work, battling out the finish with fellow Mullins entry, Uradel, to give the Irish trainer a 1-2 in the Newmarket feature handicap.
Mullins said: "Low Sun is a real hard grafter. The more we ask the more he gives. To think he was on our selling list. We had him on our selling list after Punchestown and he just kept on winning and improving.
"I wasn't looking at the two of those in the last furlong, I was looking at what was going to pass the two of them. I was hoping one would hold on. I was just delighted nothing came from out the back.
"We had this race in mind when we saw the prize money. We've another seven in the Irish Cesarewitch tomorrow and they could have come over here.
"We brought our best ones here. Apart from it being an iconic race which is a delight to have on the CV, the prize money (£500,000) was good and we aimed what we could.
"That is probably his limit. I can't see him producing another 10lb. I think we've squeezed everything we can out of him today. I don't think he would get into a Melbourne Cup.
"We will try and keep him for those big handicaps. I don't think he needs to go back over hurdles, I think we let him rest on his laurels."
What's more, Low Sun's win in the race provided jockey Seamie Heffernan with a double on the day, having landed the opener on the card, the listed Zetland Stakes, with the Aidan O'Brien-trained Norway.
View the full result for the 2018 renewal of the Cesarewitch Stakes here.
Published at 4:35 pm.