The design was chosen by 54 per cent of fans who voted at last Saturday’s home game against Toulouse Olympique.
Forty-six per cent of supporters backed an alternative Phoenix design.
The crest is being introduced alongside a name change which will see Hunslet drop the Hawks suffix from the end of this season.
Club general manager Martin Flynn said: “We always knew that it was going to be close as both crests have played a huge part in our history and are very popular amongst supporters of all ages.
“Our supporters have voted and their decision now means that we will now adopt the Rampant Lion as our new club crest.
“These are exciting times for the club and we thank our supporters for playing their part in shaping the future of our club.
“This is only the beginning of what we believe will be an exciting new era for Hunslet RLFC.”