Abstract: The SciBooNE Collaboration reports K(+) production cross section and rate measurements using high-energy daughter muon neutrino scattering data off the SciBar polystyrene (C(8)H(8)) target in the SciBooNE detector. The K(+) mesons are produced by 8 GeV protons striking a beryllium target in Fermilab Booster Neutrino Beam line (BNB). Using observed neutrino and antineutrino events in SciBooNE, we measure d(2)sigma/dpd Omega = (5.34 +/- 0.76) mb/(GeV/c x sr) for p + Be -> K(+) + X at mean K(+) energy of 3.9 GeVand angle (with respect to the proton beam direction) of 3.7 degrees, corresponding to the selected K(+) sample. Compared to Monte Carlo predictions using previous higher energy K(+) production measurements, this measurement, which uses the NUANCE neutrino interaction generator, is consistent with a normalization factor of 0.85 +/- 0.12. This agreement is evidence that the extrapolation of the higher energy K(+) measurements to an 8 GeV beam energy using Feynman scaling is valid. This measurement reduces the error on the K(+) production cross section from 40% to 14%.