Step 1) On your smartphone, launch the Youtube Kids app. Then t the right-top side of the screen, click on the cast iron, which looks like a rectangle shape.

Step 2) Make sure that your Smart Tv is connected to the same Wi-Fi network, so when you hit the Cast icon, it will display the name of your Smart TV. Click on the chromecast device on display and connect to your Smart TV.

Step 3) The casting will be successful in a few moments, after that, you can choose to run any video on your smartphone, and it will be cast on your Smart TV.

If you want to disconnect, then simply click on the cast icon on your smartphone and hit the Disconnect button.
Method 2: Casting Using Chrome Browser from your PC to Smart TV
If your Pc is connected to the same Wi-Fi network as your Smart Tv is. Then to cast on your Smart Tv, all you need is Google Chrome. If you have already installed Chrome on your PC, then you can begin casting. Of course, you can use other browsers like Firefox, but using Chrome makes the process much easier.
Step 1) Firstly, open up the Chome browser on your Pc and visit the Youtubekids.com website.

Step 2) While you are on Youtube Kids, click on the more option, which is three vertical dots located at the right-corner ner the address bar.

Step 3) From the Menu, click on the Cast option.

Step 4) Wait for a few seconds for your Chrome cast device to display, after that, click on the Sources option and select Cast Tab from the drop-down menu.

Step 5) Lastly, click on your Smart TV option available on for Cast and connect. Now, you can play and video on the browser, and it will cast to your Smart TV.

To stop casting, simply click on the cast icon and click again on the Smart TV that you are casting.
Conclusion
Youtube Kids is definitely a platform that is very beneficial for your children. If you are at home, your kids would like to watch their favorite show on Youtube Kids on a big screen, a smart Tv.
Fortunately, most of the devices come with Chromecast, and you can easily cast Youtube kids to your smart TV. However, make sure that your Smart Tv and your smartphone are connected with the same Wi-Fi network. Open up the Youtube kids app, click on the cast icon, select your smart TV, and start casting.
If you want to cast using your PC, then connect your PC to the same Wi-Fi network as your Smart Tv. Open up the Chrome browser and visit the Youtube Kids website. Click on the More option and click on the cast option from the menu. Click on the Source drop-down menu and select the cast tab. By now, your smart TV should be an option for casting, click on it and start casting.