The Formation of the Outer Solar System: an Icy Legacy (FOSSIL) survey covered 38 square degrees to capture high-cadence (10–15 min) lightcurves of Solar System objects over 1 to 4 nights to depths of . By fitting a second-order Fourier series to the lightcurves of 371 TNOs in the FOSSIL dataset we found 29 TNOs that exhibited clear periodic behaviour. Of the 29 periodic TNOs, we have obtained rotational periods for 26, four with confidence and 22 with low confidence. With the remaining three periodic TNOs, only a minimum period was obtained. One of the TNOs with a low confidence period has a period of 1.3 hours, if this period is confirmed then it will have the fastest known spin rate of any TNO. Another periodic TNO is a good candidate for a close/contact binary. Using a subset of 194 FOSSIL TNOs we found a weak correlation between the minimum absolute magnitude and lightcurve amplitude. Thus providing further support for the contentious theory that smaller TNOs are more irregular in shape.