Walker's move has been partly funded by the Rugby Football Union, who are also heavily involved in former Great Britain and Wigan captain Farrell's difficult transition from the 13-a-side code.
The 24-year-old could make his union debut during a busy Guinness Premiership programme next month, when Bath face games against London Irish, Wasps, Bristol and Newcastle.
And Walker will hope for a better start to his new career than England elite player squad member Farrell experienced, given the latter's prolonged injury struggle and then a raging debate about what his best union position - inside centre or blindside flanker - should be.
Walker is set to slot in among Bath's outside backs, and he is relishing the challenge that awaits him.
"I obviously did not sign off on the note you would want," said Walker, recalling Leeds' failure to reach this season's Grand Final.
"But this is more exciting for me than winning the Grand Final or getting to the Grand Final. I have always had this at the back of my mind, and the day has come when I have joined the club.
"I am pretty confident in the reason why I came to Bath and what I have come here to achieve.
"Rugby union is a completely new game to me. I have always been an admirer of it, but never had the chance to play it.
"I have watched a lot of games, but you are never going to get clued up by watching it. It is something I need to be practising - the coaching staff here are going to give me a lot of work to do, and I will be willing to do it."