The mode of action of Roundup Speed is similar to that of Roundup, which is a systemic, non-selective, broad-spectrum glyphosate-based herbicide.

Upon application, glyphosate is quickly taken up by the leaves and stems of the weeds and inhibits the production of the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), which is essential for the growth of weed plants, ultimately leading to the death of the weeds.