"I Swear" is a ballad written by Gary Baker and Frank J. Myers that became a hit for two acts in 1994. Initially it was a number one song on the U.S. Hot Country Singles & Tracks chart for John Michael Montgomery at the beginning of the year. His version crossed over to pop radio and climbed to #42 on the Billboard Hot 100. A few months later, All-4-One covered the song and achieved a great success in many countries.

Several months after John Michael Montgomery had released his original version, R&B vocal quartet All-4-One recorded their own version with producer David Foster. All-4-One's version hit number one in numerous countries, including the BillboardHot 100 in the U.S., where it remained for eleven consecutive weeks. It peaked at number two on the UK Singles Chart and stayed at number two for seven consecutive weeks and spent a total of 18 weeks in the chart. The All-4-One version was slightly different, in that the line "And when there's silver in your hair" from the second verse was replaced by "And when just the two of us are there."

This version was ranked at #78 on Billboard's Top 100 songs in the 50-year history of the Billboard Hot 100 chart.

In Swedish, two lyrics versions exist. One of them, "Jag svär" ("I Swear"), was written by Ingela "Pling" Forsman and recorded by Sten & Stanley on the 1995 album Musik, dans & party 10. The other, written by Anica Olsson, is called "I dag" ("Today") and was recorded in 1996 by Anders Engbergs as 2nd track on the single "Av hela mitt hjärta", and by Lotta Engberg and Jarl Carlsson i a duet on their 2005 album "Kvinna & man".

In 2003, American boy-band group B3 covered the song on their album N.Y.B3.

In 1998, a cover version was recorded by four cantopop/mandopop singers, Sandy Lam, Prudence Liew, Teresa Carpio and Chyi Yu, and was released as a single off Sandy Lam's English album "Love is the Only One". The arrangement is similar to the All-4-One version.

In 1995, brazilian duo Leandro & Leonardo covered its own version in Portuguese, called "Eu Juro".