DX centers in In‐mixed AlGaAs alloys are analyzed by deep level transient spectroscopy and capacitance vs temperature measurements. The addition of In to Si‐doped AlGaAs, with x=0.21 and 0.30, shifts the Si‐DX center to a shallower position. Under hydrostatic pressure, DX centers deepen again into the band gap. The DX center shift, and consequently, the reduction of the DX center electron occupancy, when In is added, is due to an increase of the Γ to L energy difference. In terms of band‐gap energy and DX center depth, adding 1% In is equivalent to a 1% Al reduction. Then, In mixing does not offer any new benefit to minimize DX center effects in AlGaAs‐based heterojunction devices.