Now That's What I Call Music! 45 is the 45th edition of the Now! series in the United States. It was released on February 5, 2013, on CD and from major digital retailers. The album debuted at No. 3 on the Billboard 200 albums chart with first week sales of 87,000 units. The album has sold 441,000 copies in the US as of July 2013.

Now! 45 features the number-one Billboard Hot 100 hit, "We Are Never Ever Getting Back Together" by Taylor Swift.