  We demonstrate the existence of stable knot solitons in the standard
electroweak theory whose topological quantum number $\pi_3(S^2)$ is fixed by
the Chern-Simon index of the $Z$ boson. The electroweak knots are made of the
helical magnetic flux tube of $Z$ boson which has a non-trivial dressing of the
Higgs field, which could also be viewed as two quantized flux rings linked
together whose linking number becomes the knot quantum number. We estimate the
mass of the lightest knot to be around $21 TeV$.
