The home appliance insurance firm has used Brian Coleman-Smith, currently at Cubitt Consulting, for nearly 20 years. Coleman-Smith advised on the initial approach last week.
Hogarth managing partner John Olsen heads the account, reporting to chief executive John Permund and finance director Paul Lee.
Homeserve is employing Tulchan Communications for the deal, headed by co-founder Andrew Honnor. The two firms could be worth a total of £2bn.
Domestic & General is an attractive proposition after posting a 4.3 per cent improvement in its full-year profits last week.