Some variations provide a process for producing biocarbon pellets, comprising: pyrolyzing a biomass-containing feedstock in a first pyrolysis reactor to generate a first biogenic reagent and a pyrolysis vapor; introducing the pyrolysis vapor to a separation unit, to generate a pyrolysis precipitate in liquid or solid form; contacting the first biogenic reagent with the pyrolysis precipitate, thereby generating an intermediate material; pelletizing the intermediate material, to generate intermediate pellets; optionally, drying the intermediate pellets; separately pyrolyzing the intermediate pellets in a second pyrolysis reactor to generate a second biogenic reagent and a pyrolysis off-gas; and recovering the second biogenic reagent as biocarbon pellets. Some variations provide a similar process that utilizes a carbon-containing condensed-matter material, which is not necessarily a pyrolysis precipitate. The disclosure provides improved processes for producing biocarbon compositions, especially with respect to carbon yield and biocarbon properties, such as reactivity.