Polymer diols are a class of polymeric building blocks of high interest for the synthesis of complex macromolecular edifices. Rare‐earth borohydride complexes are known as efficient initiators for the ring‐opening polymerization (ROP) of cyclic esters, directly affording α,ω‐dihydroxy‐telechelic polyesters. Here, were report the direct synthesis of poly(benzyl β‐malolactonate) (PMLABe) diols, from the ROP of racemic (benzyl β‐malolactonate) (rac‐MLABe), a valuable and renewable monomer, initiated by the homoleptic [Ln(BH4)3(thf)3] (Ln=La, Nd, and Sm) complexes. These initiators enabled the controlled ROP of this β‐lactone, affording well‐defined syndiotactic‐enriched (Pr≈0.83) PMLABes (Mn up to 21 300 g mol−1, ÐM≈1.5) as evidenced by size exclusion chromatography, 1H and 13C NMR spectroscopy, and MALDI‐ToF mass spectrometry analyses. The first and second insertions of rac‐MLABe, as assessed by DFT calculations, revealed more favorable stationary front‐side than migratory back‐side insertions, the thermodynamically and kinetically competitive ROP on two distinct arms with that on a one arm‐only, and the thermodynamically slightly favored formation of syndiotactic‐enriched PMLABes.