Joaquin made the surprise appearance Sunday night not long after winning Outstanding Performance by a Male Actor in a leading role for "Joker." He made the drive from the Shrine Auditorium to the Farmer John Packing Co. ... less than 5 miles away in L.A.

There, Joaquin joined dozens of protesters who congregate there twice a week. They call their demonstrations pig vigils. They've been happening every Wednesday and Sunday night since at least 2017.

Reportedly, the trailers stop for 2 minutes -- with Farmer John's blessing -- so activists can comfort the pigs and give them water. More than 7,000 pigs are butchered every day inside Farmer John.

Joaquin hung out with protesters and squirted water into the pigs' snouts. He told former LA TV reporter Jane Velez-Mitchell it was important to be there, saying, "Most people don’t really know of the torture and murder in the meat and dairy industry."

He went on to say, "We have moral obligations to talk about it and expose it for what it really is. We are so indoctrinated with these happy images of animals on farms, on the covers of meat containers, at restaurants and it's a lie."

Joaquin's definitely been walking the walk. Not only did he attend this protest, he reportedly convinced the Hollywood Foreign Press to serve an all-vegan menu at the Golden Globes.