<p>The objective of this study was to determine animal and pasture productivity, animal behavior, and carcass characteristics of beef steers by testing the use of overseeding winter species with or without legumes into Aruana grass pasture. The treatments evaluated were: overseeding of oat and ryegrass, with and without arrowleaf clover, in Aruana pasture, and the exclusive cultivation (monoculture) of oat and ryegrass in a crop–livestock integration area, with and without arrowleaf clover. The experiment was conducted from July 10 to October 26, 2018, at the Universidade Tecnológica Federal do Paraná – Paraná, Dois Vizinhos campus. Twenty-four castrated Angus steers, aged 25 ± 3 months and with an initial average body weight of 413.08 ± 4.56&#xa0;kg, were used. A randomized block design was adopted, with four treatments and three replications (paddocks) arranged in a 2 × 2 factorial scheme. Two animals were assigned to each paddock. Continuous grazing with a variable stocking rate was used. Forage mass, daily accumulation rate, and pasture structural composition were evaluated every 28 days. To determine average daily gain (ADG), stocking rate (SR), and live weight gain per hectare (LWG ha^− 1), the animals were weighed after a 14-hour fast from solids and liquids. Three 24-hour evaluations of ingestive behavior were carried out during the experimental period. At the end of the trial, the animals were slaughtered to assess carcass characteristics. Overseeding and the presence of legumes did not affect the nutritive value of the pasture offered to the animals; however, the presence of Aruana grass resulted in greater forage mass at the end of the grazing cycle, with less dead material, thereby improving animal performance. Steers finished on overseeded pastures showed higher average daily and per-hectare weight gain, longer grazing time, shorter rumination time, and less displacement compared with the monoculture system, resulting in better quantitative carcass characteristics.</p>