Mr Swaine won yesterday’s poll with 390 votes, finishing well clear of Conservative John Gage (253).
Ross Henley, the Liberal Democratic leader for Taunton Deane, said: "This is a fabulous result, I am really pleased for Ben Swaine.
"He will be an excellent councillor and joins two other excellent Lynford councillors in Nikki Court and Terry Murphy.
"Ben also won with the same percentage lead as our victory in May 2007."
Labour’s Martin Jevon finished third in the poll with 190 votes while Charlene Sherriff of the UK Independence Party received 59 votes.
Former Liberal Democrat councillor Julie Wood lost her right to represent Lyngford after failing to attend any “qualifying” council meetings for six months.