Harriet the Spy: Blog Wars is a 2010 television film starring Jennifer Stone that premiered on March 19, 2010, on Movie Central and The Movie Network in Canada, and on March 26, 2010, on Disney Channel in the United States. It is an adaptation of the book Harriet the Spy, by Louise Fitzhugh, the second after the 1996 Harriet the Spy film that starred Michelle Trachtenberg as Harriet. The film was produced by 9 Story Entertainment. Vanessa Morgan, who starred as Marion in the movie, went on to star in My Babysitter's a Vampire and its subsequent television series, which also aired on Disney Channel.

The film centers on Harriet M. Welsch (Jennifer Stone), an 11-year-old in the book, changed to a teenager for the film. Jennifer Stone told Popstar magazine, "We're basing it off the charm of the first book. They aged Harriet up to 16, and it still deals with mean girls, except it matures that a little. It's a bit more of mean girls having to do with gossip and heartthrobs and all that. The first book was written in the 60's so we're trying to bring it up to 2010. We're putting our own spin on it."

It is the first Disney Channel film since 1997 that was not promoted as a "Disney Channel Original Movie" and the first released through 9 Story Entertainment. It was co-produced in association with Disney Channel and Canadian pay TV channels Movie Central and The Movie Network. However, according to the Disney Channel website, the film is listed as a Disney Channel Original Movie.