This study examines reciprocal relations between toddler's numeracy and their language skills in “Germany” (N = 389, M = 31.46 months, SD = 3.34, 52.8% male) across three time points (collected between 2021 and 2023) while controlling for potential influencing factors. Cross-lagged panel models revealed that between ages 2½ and three years numeracy (β = 0.19, p < .010) and general language (β = 0.25, p < .010) development mutually predicted each other and both fostered later mathematical language (β = 0.16–0.18, p < .010). From three to four years, mathematical language predicted numeracy (β = 0.21, p < .050) and general language (β = 0.32, p < .010) development, while numeracy predicted mathematical language development (β = 0.19, p < .010). The results highlight the intertwined yet distinct roles of numeracy and general and math-specific language skills in early development.