The state

Y (2175)

is observed in the process

e^{+} e^{-} \to η Y (2175)

with a statistical significance larger than 10 standard deviations using the data collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energies between 3.7 and 4.6 GeV. This is the first observation of the

Y (2175)

in this process. The mass and width of the

Y (2175)

are determined to be

(2135 \pm 8 \pm 9) MeV / c^{2}

and

(104 \pm 24 \pm 12) MeV

, respectively, and the production cross section (

σ

) of

e^{+} e^{-} \to η Y (2175) \to η ϕ f_{0} (980) \to η ϕ π^{+} π^{-}

is at the several hundred femtobarn level. No significant signal for the process

e^{+} e^{-} \to η^{'} Y (2175)

is observed and the upper limit on

σ (e^{+} e^{-} \to η^{'} Y (2175)) / σ (e^{+} e^{-} \to η Y (2175))

is estimated to be 0.43 at the 90% confidence level. We also search for

ψ (3686) \to η Y (2175)

. No significant signal is observed, indicating a strong suppression relative to the corresponding

J / ψ

decay, in violation of the “12% rule”.

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