A lithiation of van der Waals tetrel‐arsenides GeAs and SiAs has been investigated. Electrochemical lithiation demonstrated large initial capacities of over 950 mAh g‐1 accompanied by rapid fading over successive cycling in the voltage range of 0.01‐2 V. Limiting the voltage range to 0.5‐2 V achieved more stable cycling attributed to the intercalation process with lower capacities. Ex‐situ powder X‐ray diffraction confirmed complete amorphization of the samples after lithiation, as well as recrystallization of the binary tetrel‐arsenide phases after full de‐lithiation in the voltage range of 0.5‐2 V. Solid‐state synthetic methods produces layered phases, where Si‐As or Ge‐As layers are separated by Li cations. The first layered compounds in the corresponding ternary systems were discovered, Li0.9Ge2.9As3.1 and Li3Si7As8, which crystallize in the Pbam (No. 55) and P2/m (No. 10) space groups, respectively. Semiconducting layered GeAs and SiAs accommodate extra charge from Li cations through structural rearrangement in the Si‐As or Ge‐As layers and eventually by replacement of the tetrel dumbbells with sets of Li atoms. Ge and Si monoarsenides demonstrated high structural flexibility and a mild ability for reversible lithiation.