We hypothesized that maternal overfeeding and restricted feeding during gestation would alter the collagen content, muscle fiber cross-sectional area (CSA), and meat tenderness in offspring. Pregnant ewes were fed 100% (CON), 60% (RES), or 140% (OVER) of their requirements from day 30 of gestation until parturition. Male offspring were necropsied at 282 ± 1.8 days of age. Gene expression and CSA were quantified in the longissimus (LM) and semitendinosus (STN) muscles. The Warner–Bratzler shear force (WBSF) was quantified in LM. Data were analyzed by one-way ANOVA, with diet as a fixed effect. Differences were considered significant at p ≤ 0.05 or a tendency at p ≤ 0.10. Semitendinosus CSA was smaller in OVER and RES than CON rams (p = 0.02). Longissimus CSA was larger in RES than OVER and CON rams (p = 0.002). OVER LM had reduced WBSF compared with CON rams (p = 0.03). Myogenic genes bone morphogenic protein 1 (BMP1) and paired box 7 were greater in RES LM than OVER (p ≤ 0.02). Maternal diet altered the fibrogenic genes fibronectin 1 (p = 0.07), lysyl oxidase (p = 0.07), and collagen 1A1 (COL1A1; p = 0.08) in the LM and COL1A1, COL3A1, and BMP1 (p ≤ 0.09) in the STN. Poor maternal diet during gestation alters muscle and meat characteristics that may impact meat quality.