Varuna has gone to Mr Siddaramaiah's younger son Yatheendra, a doctor who would make his debut in this election.
The chief minister had announced his choice last week -- a day before the Congress list was announced. On Sunday, the party -- which won 122 of the state's 224 seats in 2013 -- named 218 candidates.
Chamundeshwari is the hilltop goddess who presides over Mysuru and is worshipped with great fervour during the annual Dasara festival. While Mr Siddaramaiah lost only two elections from here, his victory in 2006 with a wafer-thin margin had pushed him towards the safe seat Varuna.
That time, Mr Siddaramaiah was contesting a by-poll after changing camp from HD Deve Gowda's JD(S) to the Congress. He won with around 250 votes. After the delimitation in 2008, he shifted to Varuna, since most of his supporters became part of that constituency. He won the 2008 and 2013 elections from Varuna.
This time too, winning Chamundeshwari may be an uphill task. There is speculation in the Congress camp of a tacit understanding between the JD(S) and the BJP, and the opposition is likely to do all it can to deliver to the Congress the embarrassment of having their chief minister lose.
For Mr Siddaramaiah, leaving his home belt Mysuru would have appeared as a lack of confidence, which the Congress could not afford in the run-up to the tough election, which the BJP is going all-out to win.
Mr Siddaramaiah is seen as the face of the Congress in the state and the campaign sometimes appears to be a battle between the chief minister and the achievements his government claims, against the BJP central leadership. Prime Minister Narendra Modi has addressed several rallies in Karnataka, while BJP chief Amit Shah has been a frequent visitor.
By standing only from one seat, Mr Siddaramaiah is seen as sending out a message that he believes that the goddess Chamundeshwari is on his side.