The adverse health impacts of early infant stunting can be partially ameliorated by early catch-up growth. Few studies have examined predictors of and barriers to catch-up growth to identify intervention points for improving linear growth during infancy. This study aimed to estimate the prevalence of, and factors associated with, catch-up growth among infants in Pakistan. A longitudinal study of mother-infant dyads (n = 1,161) was conducted in rural Sindh province, with enrolment between December 2015 and February 2016 (infants aged 0.5-3 months), and follow-up (n = 1035) between November 2016 and January 2017 (infants aged 9-15 months). The outcome was catch-up growth (change in conditional length-for-age z-scores >0.67 between baseline and endline). Associated factors were examined using multivariable logistic regression analyses. The prevalence of stunting was 45.3% at baseline and 60.7% at follow-up. 22.8% of infants exhibited catch-up growth over this period. Factors positively associated with catch-up growth included maternal height (odds ratio (OR) = 1.08 [1.05-1.11]), household wealth (OR = 3.61 [1.90-6.84]), maternal (OR = 2.43 [1.30-4.56]) or paternal (OR = 1.46 [1.05-2.03]) education, and households with two or more adult females (OR = 1.91 [1.26-2.88]). Factors negatively associated with catch-up growth were two (OR = 0.64 [0.45-0.89]) or three or more (OR = 0.44 [0.29-0.66]) preschool children in the household and the infant being currently breastfed (OR = 0.59 [0.41-0.88]). Catch-up growth was exhibited among approximately a quarter of infants despite living in challenging environments associated with extremely high rates of early infant stunting. Several modifiable factors were identified that might represent suitable programme intervention points to off-set early infant stunting in rural Pakistan.