It follows the introduction of free lunches for all pupils in primary one to three by the Scottish Government at the start of January 2015.
It is estimated this will save families £380 annually and ministers say it helps children focus on their studies.
SNP MSP George Adam said: “One year on from the introduction of free school meals, 259,000 pupils are now registered to receive them – almost double the number benefitting last year.
“For each and every registered child this will save £380 a year – a substantial saving at a time of tight family budgets. This policy underscores the SNP government’s ongoing commitment to reducing household bills – alongside the Council Tax freeze, the provision of free universal childcare and free prescriptions.
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“The benefits of free school meal provision are not just financial – the policy ensures young children get a healthy and nutritious meal every day, helping them concentrate better on their studies and to achieve better academic results.
“The SNP is committed to reducing poverty and inequality in Scotland – and the continued provision of universal benefits like free school meals are key to achieving the fairer society we all want to see.”
The free meals announcement was made by Alex Salmond in 2014 after UK ministers announced plans to offer pupils in the first three years of primary school in England a free cooked lunch.
An evaluation of the English pilot on free school meals, commissioned five years ago, found that there was some positive impact on nutrition and health and an increase in attainment strongest amongst pupils from poorer families and amongst those doing badly in their studies.