Layered double hydroxides (LDHs) have been intensively studied for phosphate (P_i) removal but suffer from poor stability and low sorption affinity under ambient conditions. In this paper, well crystallized Mn^IIFe^IIFe^III-Cl, Mn^IIFe^III-CO₃ and novel Mn^IVFe^III-CO₃ LDHs were synthesized. The LDHs show fast P_i sorption with 90 % uptake within 20 min, and high P_i sorption capacity of 11 mg P/g at low solution P_i concenrations of 0.1 mg P/L, corresponding to a very high P_i sorption affinity (K_d 1.1 × 10⁵ L/kg). Fast Mn^II dissolution from the Mn^IIFe^IIFe^III-Cl LDHs and formation of MnFe₂O₄ at pH 7 were observed in aqueous suspensions of non-oxidized material where up to 70% of total Mn was released within 2 h. However, when interlayer Cl^- was exchanged with CO₃²⁻, much lower Mn dissolution (5.4%) was observed. Furthermore, after oxidation of Mn^II to Mn^IV, the obtained Mn^IVFe^III-CO₃ LDH maintained the layered structure of LDH and the particles were surrounded by birnessite nanorods. The Mn^IVFe^III-CO₃ LDH showed excellent stability but lower P_i sorption capacity. However, a high sorption affinity was maintained which is attributed to more positively charged Fe-centered sorption sites. XPS and ATR-FTIR data together with DFT calculations demonstrated that P_i was mainly sorbed via the formation of mononuclear mono- and bidentate P_i surface complexes on planar LDH particle surfaces.