Rater training is necessary to accurately evaluate fundamental motor skills among children with developmental disabilities (DD). The purpose of this pilot study was to examine the impact of an online rater training program for novice raters on scoring accuracy of the run and two-hand strike skills on the Test of Gross Motor Development-Third Edition (TGMD-3) among children with DD. A training program was created consisting of two units/modules. The first module introduced the TGMD-3 and the second outlined behavior, movement characteristics, and correct scoring for the run and two-hand strike for children with DD. Forty-one novice raters completed three rounds of training and scoring. Data analysis compared the change of rating accuracy of novice raters on the run and two-hand strike skills of the TGMD-3 across three different occasions. There was a statistically significant positive impact on the scoring accuracy of novice raters for the run, two-hand strike skills, and the total skill score (p < 0.001). The TGMD-3 online rater training program for novices in the present study could provide a model training program to improve the accuracy of scoring fundamental motor skills among children with DD.