Meandering rivers are prone to dramatic changes with avulsion processes, which include a series of geomorphological adjustments in the fluvial landscape. However, research into how the floodplain characteristics influence this process, as well as what are the geomorphological adjustments in the parent channel is still scarce. The lower course of the Peixe River, located in the southeastern region of Brazil, has a multi-thread reach with a ∼ 14 km channel long formed by an avulsion in the 1970 s, which provides an excellent opportunity to evaluate avulsion aspects. We use remote sensing to evaluate morphological changes in the channels involved in the avulsion, and floodplain features as setups. We also investigated, with fieldwork measurements, potential adjustments in the channel affected by avulsion. The floodplain width variation regulated the avulsion extent. Planform analyses of the channels involved in the avulsion indicated distinct differences in sinuosity, and a development to an approximated equivalence in the current width of the two channels. The bank elevation in the parent channel showed a decrease with a strong adjustment in the downstream direction, and the absence of significant variation of this parameter in the reach with flow bifurcation. Sedimentary analyses in channel banks showed two deposits with significantly different sedimentometric characteristics and concentration of organic matter, described as bottom and top layers, the top being coarser than the bottom layer. The top layer has a significant variation of muddy sediments and organic matter in the avulsion reach, however, in the bottom layer this pattern was not observed. Setups in the Peixe River avulsion are associated with intrinsic factors from meandering dynamics, and evidence emerges from this study to test anthropogenic influences. Sedimentological parameters investigated in the parent channel appear more adjusted to the bifurcation flow than morphological parameters.