Oprah Winfrey has given an energetic speech in support of Kamala Harris during the Democratic National Convention.

The media mogul made a surprise appearance on the third night of the convention in Chicago – where her famous TV talk show was filmed for many years.

The actress and author – a registered independent voter – gave her full backing to Ms Harris and her running mate Tim Walz for November’s US presidential election.

She also used her speech to criticise Ms Harris’s rival, former US president and Republican nominee Donald Trump who, many years ago, she suggested could one day be elected to the Oval Office.

Winfrey offered a full-throated endorsement of Ms Harris and characterised her campaign by singing out, “Joy!”.

“Decency and respect are on the ballot in 2024,” she said, adding: “Let us choose common sense over nonsense.”

Wednesday night’s convention theme was “Freedom”. Backed by Beyonce’s song of the same name, which the musician has authorised Ms Harris’s campaign to use, the word flashed on the video screen and in speech after speech.

Democrats firmly tied it to the fight over women’s reproductive rights but they also used the freedom argument to slam Republicans on other social issues, from gay rights to the spread of book bans in schools.

Winfrey said of freedom: “Every now and then, it requires standing up to life’s bullies.”

Oprah Winfrey speaks during the Democratic National Convention
Winfrey said decency and respect are on the ballot in November’s presidential election (AP Photo/J. Scott Applewhite)

Other celebrities appearing at the convention on Wednesday included actress Mindy Kaling, who hosted parts of the evening, and musicians Stevie Wonder and John Legend, who both performed on the night.

Legend covered the songs of Prince, who was born in Minnesota, the state Mr Walz is governor for.

Pop star Pink is slated to perform on the final night of the convention.