Using the 12-m APEX telescope, we have detected redshifted emission from the 157.74 mu m [CII] line in the z = 4.4074 quasar BRI 1335-0417. The linewidth and redshift are in good agreement with previous observations of high-J CO line emission. We measure a [CII] line luminosity, L([CII]) = (16.4 +/- 2.6) x 10(9) L(circle dot), making BRI 1335-0417 the most luminous, unlensed [CII] line emitter known at high-redshift. The [CII]-to-FIR luminosity ratio of (5.3 +/- 0.8) x 10(-4) is similar to 3x higher than expected for an average object with a FIR luminosity L(FIR) = 3.1 x 10(13) L(circle dot), if this ratio were to follow the trend observed in other FIR-bright galaxies that have been detected in [CII] line emission. These new data suggest that the scatter in the [CII]-to-FIR luminosity ratio could be larger than previously expected for high luminosity objects. BR1335-0417 has a similar FIR luminosity and [CII]/CO luminosity compared to local ULIRGS and appears to be a gas-rich merger forming stars at a rate of a few thousand solar masses per year.