I was searching for good non-veg food in Mysuru and I got 8 out of 10 people suggesting RRR restaurant. It is well known for Andhra style biryani.
Food is very good, with very good taste. You will not resist to go twice in a week.
Only thing is it is a crowded place, that shows it's famous and not having much off a variety.
If you want to have good biryani, must visiti RRR.

This place is known for its biryani, which is pretty good. However, given its popularity, it is quite crowded and not all covid protocols were followed. Recommend going early/late and not during peak lunch hours.

I have stayed in Mysore in the past and know all the restaurants. I always loved having a meal at RRR. Its Andhra style Cuisine is tasty. Whenever I visited Mysore, I made it a point to visit RRR. Recently when i when i went to RRR, I found that the place is shifted. I couldnt get a seat and hence opted for Pickup of Food. I ordered Thali, Biryani and Chicken. To my surprise, i noticed that quality has comedown significantly. It is a big let down for me.

Upon our visit to Mysore we went to RRR AC Restaurant for the first time..
Even now (Dec'2020) the place was super crowded and we had to wait for tables.
We enjoyed having Veg Meals , Chicken 64 . Another day tried Mutton Biryani which was Yum. Chicken and mutton roast was ok (bit spicy). If you come to Mysore and like Non veg food do visit. It's worth it
Pics attached

A quick introduction about me I am from Mysore lived most of my childhood and adolescence here however like all grownup I migrated to Bangalore for a job and settled there that said I visit this restaurant whenever I travel to Mysore on business/ pressure, I recently visited this restaurant on 3rd December 2020 with my mother we ordered two mutton biryani dine in two mutton biryani parcel/takeaway and one chicken 64 dine in, the combination of mutton biryani and chicken 64 is the way to go for non vegetarians / meat eaters however what we noticed is the serving plate size and quantity has drastically reduced and you are left craving for more after you finish your lunch not just this you only receive two pieces of mutton the size of your thumb and that too for a whopping price of Rs.250 / USD 3.4 there are much better places which serve much larger portions of biryani at lesser prices which are equally good if not better than this place, I still remember the 90s when my dad used to take us to this restaurant at least once in two months as back then people didn't have much to spend and most of them ate at home and occasionally went out dinning, Up till 2009-2010 the taste used to be similar as if the same guy/women used to cook their biryani but later the taste has varied and in between the biryani had become too spicy and the way of cooking had changed drastically come 2017 onwards the recipe changed and its was just a bit likable, I am saying this as I have tasted their biryani for years but now the establishment has turned a bit greedy and is riding the fan wave due to online reviewers and old people recommendation as this used to be a good place long ago till 2010 but now the taste of the biryani is not that impressive and the portion size of food (the rice and meat) is not justified for the price, I would suggest you pass this one if you are new to Mysore and try Hanumanth Biryani, Nasheman Hotel (located quite close by but small joints for take always only) or better yet the restaurant Parklane Hotel right next to the new RRR on sri harsha road serves some amazing mutton fried rice that you will not regret, Hope my review helps you make an informed decision