A field experiment was conducted at Woreta ATVET College demonstration farm in 2020/2021 irrigation season to determine the effect of different rates of nitrogen (42, 84, 126 and 168 kg N ha -1 ) and intra-row spacing (3, 5, 7 and 9 cm) on growth and yield of onion. The experiment was laid out in a randomized complete block design (RCBD) of factorial arrangement with three replications. Growth and yield data were collected following their standard procedures and analyzed using SAS 9.0 software. The results of ANOVA showed that the main effects of intra-row spacing and nitrogen rate as well as their interaction, significantly affected days to maturity, plant height, leaf number, leaf length, bulb weight, bulb length, bulb diameter, marketable bulb yield, unmarketable bulb yield and total bulb yield. The highest significant plant height (54.73 cm), leaves length (49.36 cm), leaves number per plant (12.56), days to maturity (120 days), bulb weight (83.72 g), bulb diameter (7.01 cm) and bulb length (7.14 cm) were recorded from onion plants supplied with 168 kg ha -1 N combined with 9 cm of intra row spacing. The highest marketable bulb yield (30.72 t ha -1 ) was recorded from treatment combination of 84 kg ha -1 N and 5 cm of intra row spacing. Onion plants supplied with 42 kg ha -1 nitrogen fertilizer and planted at narrow intra row spacing were inferior in almost all growth and yield components. The highest net benefit of ETB 319,576.00.00 with an acceptable marginal rate of return (1339.61%) was recorded from the combination of 84 kg N ha -1 and 5 cm intra-row spacing. Based on the results of the present study, the combination of 84 kg ha -1 N and 5 cm of intra row spacing can be recommended for economical production of onion in the study area since it recorded the highest net benefit with acceptable marginal rate of return. However, the results are limited to one season and location, the experiment should be repeated in different areas and seasons for forceful recommendations.