How to style MUI Tooltip?

The other popular answer (by André Junges) on this question is for the 0.x versions of Material-UI. Below I've copied in my answer from Material UI's Tooltip - Customization Style which addresses this for v3 and v4. Further down, I have added a version of the example using v5.

Below are examples of how to override all tooltips via the theme, or to just customize a single tooltip using withStyles (two different examples). The second approach could also be used to create a custom tooltip component that you could reuse without forcing it to be used globally.

import React from "react";
import ReactDOM from "react-dom";

import {
  createMuiTheme,
  MuiThemeProvider,
  withStyles
} from "@material-ui/core/styles";
import Tooltip from "@material-ui/core/Tooltip";

const defaultTheme = createMuiTheme();
const theme = createMuiTheme({
  overrides: {
    MuiTooltip: {
      tooltip: {
        fontSize: "2em",
        color: "yellow",
        backgroundColor: "red"
      }
    }
  }
});
const BlueOnGreenTooltip = withStyles({
  tooltip: {
    color: "lightblue",
    backgroundColor: "green"
  }
})(Tooltip);

const TextOnlyTooltip = withStyles({
  tooltip: {
    color: "black",
    backgroundColor: "transparent"
  }
})(Tooltip);

function App(props) {
  return (
    <MuiThemeProvider theme={defaultTheme}>
      <div className="App">
        <MuiThemeProvider theme={theme}>
          <Tooltip title="This tooltip is customized via overrides in the theme">
            <div style={{ marginBottom: "20px" }}>
              Hover to see tooltip customized via theme
            </div>
          </Tooltip>
        </MuiThemeProvider>
        <BlueOnGreenTooltip title="This tooltip is customized via withStyles">
          <div style={{ marginBottom: "20px" }}>
            Hover to see blue-on-green tooltip customized via withStyles
          </div>
        </BlueOnGreenTooltip>
        <TextOnlyTooltip title="This tooltip is customized via withStyles">
          <div>Hover to see text-only tooltip customized via withStyles</div>
        </TextOnlyTooltip>
      </div>
    </MuiThemeProvider>
  );
}
const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);

Here is documentation on tooltip CSS classes available to control different aspects of tooltip behavior: https://material-ui.com/api/tooltip/#css

Here is documentation on overriding these classes in the theme: https://material-ui.com/customization/components/#global-theme-override

Here is a similar example, but updated to work with v5 of Material-UI (pay attention that it works in 5.0.3 and upper versions after some fixes). It includes customization via the theme, customization using styled, and customization using the sx prop. All of these customizations target the "tooltip slot" so that the CSS is applied to the element that controls the visual look of the tooltip.

import React from "react";
import ReactDOM from "react-dom";

import { createTheme, ThemeProvider, styled } from "@mui/material/styles";
import Tooltip from "@mui/material/Tooltip";

const defaultTheme = createTheme();
const theme = createTheme({
  components: {
    MuiTooltip: {
      styleOverrides: {
        tooltip: {
          fontSize: "2em",
          color: "yellow",
          backgroundColor: "red"
        }
      }
    }
  }
});
const BlueOnGreenTooltip = styled(({ className, ...props }) => (
  <Tooltip {...props} componentsProps={{ tooltip: { className: className } }} />
))(`
    color: lightblue;
    background-color: green;
    font-size: 1.5em;
`);

const TextOnlyTooltip = styled(({ className, ...props }) => (
  <Tooltip {...props} componentsProps={{ tooltip: { className: className } }} />
))(`
    color: black;
    background-color: transparent;
`);

function App(props) {
  return (
    <ThemeProvider theme={defaultTheme}>
      <div className="App">
        <ThemeProvider theme={theme}>
          <Tooltip title="This tooltip is customized via overrides in the theme">
            <div style={{ marginBottom: "20px" }}>
              Hover to see tooltip customized via theme
            </div>
          </Tooltip>
        </ThemeProvider>
        <BlueOnGreenTooltip title="This tooltip is customized via styled">
          <div style={{ marginBottom: "20px" }}>
            Hover to see blue-on-green tooltip customized via styled
          </div>
        </BlueOnGreenTooltip>
        <TextOnlyTooltip title="This tooltip is customized via styled">
          <div style={{ marginBottom: "20px" }}>
            Hover to see text-only tooltip customized via styled
          </div>
        </TextOnlyTooltip>
        <Tooltip
          title="This tooltip is customized via the sx prop"
          componentsProps={{
            tooltip: {
              sx: {
                color: "purple",
                backgroundColor: "lightblue",
                fontSize: "2em"
              }
            }
          }}
        >
          <div>
            Hover to see purple-on-blue tooltip customized via the sx prop
          </div>
        </Tooltip>
      </div>
    </ThemeProvider>
  );
}
const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);

Documentation on changes to the theme structure between v4 and v5: https://mui.com/guides/migration-v4/#theme

Tooltip customization examples in the Material-UI documentation: https://mui.com/components/tooltips/#customization

This answer is out of date. This answer was written in 2016 for the 0.x versions of Material-UI. Please see this answer for an approach that works with versions 3 and 4.

well, you can change the text color and the element background customizing the mui theme.

color - is the text color

rippleBackgroundColor - is the tooltip bbackground

Example: Using IconButton - but you could you the Tooltip directly..

import React from 'react';
import IconButton from 'material-ui/IconButton';
import MuiThemeProvider from 'material-ui/lib/styles/MuiThemeProvider';
import getMuiTheme from 'material-ui/lib/styles/getMuiTheme';

const muiTheme = getMuiTheme({
  tooltip: {
    color: '#f1f1f1',
    rippleBackgroundColor: 'blue'
  },
});

const Example = () => (
  <div>
    <MuiThemeProvider muiTheme={muiTheme}>
        <IconButton iconClassName="muidocs-icon-custom-github" tooltip="test" />
    </MuiThemeProvider>
  </div>
);

You can also pass a style object for the Tooltip (in IconButton it's tooltipStyles) - but these styles will only be applied for the root element.

It's not possible yet to change the label style to make it wrap in multiple lines.

I ran into this issue as well, and want for anyone seeking to simply change the color of their tooltip to see this solution that worked for me:

import React from 'react';
import { makeStyles } from '@material-ui/core/styles';

import Tooltip from '@material-ui/core/Tooltip';
import Button from '@material-ui/core/Button';
import DeleteIcon from '@material-ui/icons/Delete';

const useStyles = makeStyles(theme => ({
  customTooltip: {
    // I used the rgba color for the standard "secondary" color
    backgroundColor: 'rgba(220, 0, 78, 0.8)',
  },
  customArrow: {
    color: 'rgba(220, 0, 78, 0.8)',
  },
}));

export default TooltipExample = () => {
  const classes = useStyles();

  return (
    <>
      <Tooltip
        classes={{
          tooltip: classes.customTooltip,
          arrow: classes.customArrow
        }}
        title="Delete"
        arrow
      >
        <Button color="secondary"><DeleteIcon /></Button>
      </Tooltip>
    </>
  );
};

If you want to change text color , font-size ... of Tooltip there is a simple way.

You can insert a Tag inside Title of Martial Ui Tooltip for example :

<Tooltip title={<span>YourText</span>}>
   <Button>Grow</Button>
</Tooltip>

then you can style your tag anyhow you want.

check below Example :

MUI v5 Update

You can customize the Tooltip by overriding the styles in the tooltip slot. There are 3 ways to do that in v5. For reference, see the customization section of Tooltip. More examples of sx prop and createTheme can be seen here and here.

styled()

const ToBeStyledTooltip = ({ className, ...props }) => (
  <Tooltip {...props} classes={{ tooltip: className }} />
);
const StyledTooltip = styled(ToBeStyledTooltip)(({ theme }) => ({
  backgroundColor: '#f5f5f9',
  color: 'rgba(0, 0, 0, 0.87)',
  border: '1px solid #dadde9',
}));

sx prop

<Tooltip
  title="Add"
  arrow
  componentsProps={{
    tooltip: {
      sx: {
        bgcolor: 'common.black',
        '& .MuiTooltip-arrow': {
          color: 'common.black',
        },
      },
    },
  }}
>
  <Button>SX</Button>
</Tooltip>

createTheme + ThemeProvider

const theme = createTheme({
  components: {
    MuiTooltip: {
      styleOverrides: {
        tooltip: {
          backgroundColor: 'pink',
          color: 'red',
          border: '1px solid #dadde9',
        },
      },
    },
  },
});