Observation of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="italic">B</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow><mml:mi/><mml:mo>→</mml:mo><mml:mi/><mml:mrow><mml:msub><mml:mrow><mml:mi>χ</mml:mi></mml:mrow><mml:mrow><mml:mi>c</mml:mi><mml:mn>0</mml:mn><mml:mn/></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msup><mml:mrow><mml:mi>K</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>

Using a sample of $31.3\ifmmode\times\else\texttimes\fi{}{10}^{6}B\overline{B}$ pairs collected with the Belle detector at the $\ensuremath{\Upsilon}(4S)$ resonance, we make the first observation of the charged $B$ meson decay to ${\ensuremath{\chi}}_{c0}$ and a charged kaon. The measured branching fraction is $B({B}^{+}\ensuremath{\rightarrow}{\ensuremath{\chi}}_{c0}{K}^{+})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}({6.0}_{\ensuremath{-}1.8}^{+2.1}\ifmmode\pm\else\textpm\fi{}1.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$, where the first error is statistical, and the second is systematic.