[1] Pärn formerly worked as a plant ecologist; his career in animation began when he accepted Rein Raamat's proposal to make a design for Kilplased (1974).

Pärn's most important films are considered to be Triangle (1982), Breakfast on the Grass (1987), Hotel E (1992), 1895 (co-directed by Janno Põldma, 1995) and Night of the Carrots (1998).

In his footsteps (and occasionally copying his style to a large degree) have followed numerous new generation Estonian film makers, most notably Ülo Pikkov and Priit Tender.

Influences of Pärn's graphical style can also be seen in such commercial animated series as Rugrats and AAAHH!!!

Divers in the Rain (2010), co-directed with his wife Olga Pärn, became the most successful Estonian animated film of all time with its 18th award at KROK International Animated Film Festival in Ukraine.