Aim Malnutrition is common in older adults, and contributes to the risk of falls and functional impairment. Gait performance also contributes to falls and functional impairment; however, the association between malnutrition and gait performance remains unclear. The purpose of the present study was to investigate the association between malnutrition risk and gait performance. Methods The study participants included 204 community‐dwelling older adults with a mean age of 73.4 ± 4.3 years. Nutritional status was evaluated using the short version of the Mini‐Nutritional Assessment. A score of 11 points was used as the cut‐off, and the participants were categorized into two groups: ≤11, malnutrition‐risk group; and ≥12, well‐nourished group. Gait performance was assessed by gait speed and walking smoothness. Walking smoothness was quantified by harmonic ratios (HR), which were derived from vertical (VT), mediolateral (ML) and anteroposterior trunk accelerations, recorded during over‐ground walking. Skeletal muscle mass index, handgrip strength and physical functions were also measured. Results HR in the ML direction was significantly lower in the malnutrition‐risk group than the well‐nourished group (P = 0.002); however, no differences between the two groups were observed in gait speed or HR in the VT and anteroposterior directions. The relationship between malnutrition and HR in the ML direction was independent of skeletal muscle mass index, handgrip strength, physical function, gait speed, and other confounders (P < 0.05). Conclusions In community‐dwelling older adults, malnutrition is related to decreased walking smoothness in the ML direction, suggesting that nutritional status affects lateral trunk control during walking. Geriatr Gerontol Int 2017; 17: 1155–1160.