Preventing hardware back button android for React Native

You need to return true, if you want to disable the default back button behavior.

Here is a sample component which will block the user from going back to previous screen.

import React, {Component,} from 'react';
import {
    View,
    Text,
    BackHandler,
    ToastAndroid,
} from 'react-native';

class BackButtonDemo extends Component {
    componentDidMount() {
        BackHandler.addEventListener('hardwareBackPress', this.handleBackButton);
    }

    componentWillUnmount() {
        BackHandler.removeEventListener('hardwareBackPress', this.handleBackButton);
    }

    handleBackButton() {
        ToastAndroid.show('Back button is pressed', ToastAndroid.SHORT);
        return true;
    }

    render() {
        return (
            <View>
                <Text>Back button example</Text>
            </View>
        );
    }
}

module.exports = BackButtonDemo;

Note:

Also remove this.props.navigator.pop(); from your solution.

Navigator pop function will take the user to the previous screen rendered by Navigator.