Pentin will join the agency on Monday 28 April. He will lend his expertise on accounts including O2 and comparethemarket.com, and will report to Matthew Heath, Lida’s chairman and chief strategy officer.
Heath said: "The strategies that answer today’s client briefs need to keep pace with new tech and an economically-savvier consumer.
"Richard’s extensive insight and knowledge around building and implementing large, global CRM, digital and social strategies will add another dimension to the agency and the work we produce."
Pentin will not have equity in the business. Lida has one other strategy partner, Caroline Parkes, who joined Lida's parent M&C Saatchi group in 2010.
Pentin began working full-time at TMW in 2007 as a group account director, and was promoted to group planning director in 2010.
He has also worked at agencies including Chemistry, (now Publicis Chemistry) Partners Andrews Aldridge and Proximity, and on brands including Harley Davidson, Sony Mobile and Lloyds bank.
Earlier this month, Lida won the Alzheimer’s Society’s digital and direct account after a competitive pitch.