A global transformation towards sustainable food systems is crucial for delivering on climate change mitigation targets worldwide. In high- and middle-income settings, plant-based meat and dairy alternatives present potential substitutes for animal sourced foods, and a pathway to transition to more sustainable diets. We examined plant-based alternative foods (PBAF) consumption trends in the UK by analysing repeated cross-sectional food consumption data from the National Diet and Nutrition Survey 2008-2019. Dietary data for 15,655 individuals aged 1.5 years and over were analysed to assess aggregate change in intake of PBAF and six other food groups that play a role in transformative dietary change. Characteristics associated with consumption of PBAF were explored using logistic regression, and consumption patterns in high and low meat consumers were explored by examining intake of potential animal product substitute food groups. The proportion of individuals reporting consumption of any PBAFs increased from 6.7% in 2008-2011, to 13.1% in 2017-2019 (p < 0.01). Compared to 2008-2011 PBAF consumption rose by 115% in 2017-2019 (p < 0.01). Females were 46% more likely than males to report consumption of PBAF (p < 0.01). Millennials (age 24-39 years) were the most likely generation to report PBAF consumption (p < 0.01 compared to generation Z (age 11-23 years) and traditionalists (age 75+ years)), as were individuals of the highest income tertile (p < 0.01). Among "low meat consumers", PBAF consumption was on average higher than "high meat consumers" (18.6 g versus 4.8 g PBAF per day, p < 0.01). Our results support the hypothesis of a pivotal role of PBAF in the transition towards sustainable food systems in the UK, by demonstrating they are becoming increasingly popular among UK consumers. This highlights the urgent need to assess in detail the environmental and health impacts of large scale and population-wide consumption of PBAF in comparison to their animal-based equivalents.