Lim was a principal engineer at M1. As a politician, Lim describes himself a "dedicated & determined" leader. He first joined as a member of the Singapore People's Party as part of the Singapore Democratic Alliance, he contested and lost the 2001 and 2006 Singaporean general elections. Lim left Singapore People's Party to join Singapore Justice Party in 2011, he also formed a community service group Sinpo under the umbrella of Singapore Democratic Alliance and Singapore Justice Party, and later contested the 2011 Singaporean general election, and lost, having only garnered 4.5% of the valid votes. He held Singapore's first online rally during the 2013 Punggol East by-election, on 21 January 2013, during which he spoke about the cost of living and property prices in Singapore. The online rally drew much criticism, most of which concerned his poor command of English. Lim, in contrast, hailed the online rally as a "great achievement" and also replied:
Everyone is not perfect. The most important thing is that we are learning, and I'm learning and there are leaders at the beginning when they come into politics, their English is also not as good as mine, but nevertheless most importantly is never give up and be sincere and have the heart to serve the people.
During the by-election, it was reported that some residents admired his "underdog indefatigability". However, Lim ultimately lost the by-election, finishing fourth and last with 168 votes. He became the second candidate to have forfeited his deposit twice, and at 0.57% of the valid votes, he topped Teo Kim Hoe's former record as the lowest percentage garnered in an election since the independence of Singapore in 1965. On 2 May 2013, his community service group Sinpo was renamed to DL's Caring Community. Lim led the SDA team at Pasir Ris-Punggol GRC during the 2015 elections, but his team was defeated by the PAP by a vote share of 72.89%-27.11%. In the 2020 elections, Lim led his SDA team to face off the ruling People's Action Party team anchored by heavyweight Senior Minister and Coordinating Minister for National SecurityTeo Chee Hean and the newly-formed Peoples Voice team in the alliance's sole contesting division and the only three-cornered fight in GRC, Pasir Ris–Punggol Group Representation Constituency where the alliance contested thrice in the 2006 elections, 2011 elections and 2015 elections. His SDA team lost to the PAP team.
Personal life
Desmond Lim is married and has a son. In a short interview with The New Paper, Lim revealed that he didn't attend kindergarten during his early childhood. This resulted in his poor command of English pronunciation, which was made fun of by netizens during the SDA's Online Rally during the 2013 Punggol East By-Election. However he assured residents that he is able to communicate in Mandarin to make up for the lack of proficiency in English. Lim further emphasised that in the Parliament of Singapore, members are allowed to speak in any of the four official languages. Lim also attributed the poor pronunciation of certain English words in the Online Rally to the fact that he was unfamiliar with the script which was only given to him 5 minutes before recording and that the recording was done late at night. He also emphasised YouTube's poor handling of his speech, resulting in skewed subtitles.
