Exhibit 99.1

NEWS RELEASE

FOR IMMEDIATE RELEASE

CENTURY BANCORP, INC. ANNOUNCES RECORD CORE EARNINGS FOR 2017, UP 25%, NET

INCOME DOWN 9.1% AS A RESULT OF A DEFERRED TAX REMEASUREMENT CHARGE OF

$8.4MM; ASSET GROWTH TO RECORD $4.8 BB; REGULAR DIVIDEND DECLARED

Medford, MA, January 16, 2018—Century Bancorp, Inc. (NASDAQ:CNBKA) (www.centurybank.com) (“the Company”) today announced net income of $22.3 million for the year ended December 31, 2017, or $4.01 per Class A share diluted, a decrease of 9.1% compared to net income of $24.5 million, or $4.41 per Class A share diluted, for the same period a year ago. The Company’s core earnings⁽¹⁾ increased by $6.2 million or 25.3% from $24.5 in 2016 to a record $30.7 million in 2017.

On December 22, 2017, the Tax Cuts and Jobs Act (the “Tax Act”) was enacted, which lowered the Company’s federal tax rate from 34% to 21%. As a result of the rate reduction, the Company recorded a reduction in the value of its net deferred tax asset resulting in a charge of $8.4 million to income tax expense.

Total assets increased 7.2% from $4.46 billion at December 31, 2016 to $4.79 billion at December 31, 2017. For the quarter ended December 31, 2017, net income totaled $25,000 or $0.00 per Class A share diluted, a decrease of 99.6% compared to net income of $6,500,000, or $1.17 per Class A share diluted, for the same period a year ago.

Net interest income totaled $85.6 million for the year ended December 31, 2017 compared to $74.1 million for the same period in 2016. The 15.6% increase in net interest income for the period is primarily due to an increase in average earning assets and an increase in the net interest margin. The net interest margin increased from 2.12% on a fully taxable equivalent basis in 2016 to 2.25% for the same period in 2017. This was primarily the result of an increase in rates on earning assets and prepayment penalties collected. The average balances of earning assets increased by 8.1% combined with a similar increase in average deposits. Also, interest expense increased 23.0% primarily as a result of an increase in rates and an increase in deposit balances.

The provision for loan losses increased by $415,000 from $1.4 million for the year ended December 31, 2016 to $1.8 million for the same period in 2017, primarily as a result of an increase in loan growth offset, somewhat, by changes in historical loss factors.

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The Company’s effective tax rate increased from (1.5%) for 2016 to 32.9% for the same period in 2017. This was primarily as a result of a reduction in the value of its net deferred tax asset resulting in a charge of $8.4 million to income tax expense as a result of the Tax Act as previously discussed. An increase in taxable income also contributed to the increase in the effective tax rate for 2017.

At December 31, 2017, total equity was $260.3 million compared to $240.0 million at December 31, 2016. The Company’s equity increased primarily as a result of earnings and a decrease in other comprehensive loss, net of taxes, offset somewhat by dividends paid. Other comprehensive loss, net of taxes, decreased primarily as a result of a decrease in unrealized losses on securities transferred from available-for-sale to held-to-maturity and a decrease in unrealized losses on securities available-for-sale. The reduction in the value of the Company’s deferred tax asset of $8.4 million impacted the Company’s total equity as a reduction to retained earnings.

The Company’s leverage ratio stood at 6.70% at December 31, 2017, compared to 6.28% at December 31, 2016. The increase in the leverage ratio was due to an increase in stockholders’ equity, offset somewhat by an increase in quarterly average assets. Book value as of December 31, 2017 was $46.75 per share compared to $43.11 at December 31, 2016.

The Company’s allowance for loan losses was $26.3 million or 1.21% of loans outstanding at December 31, 2017, compared to $24.4 million or 1.27% of loans outstanding at December 31, 2016. The change in the ratio of the allowance for loan losses to loans outstanding, when compared to December 31, 2016, was primarily due to changes in portfolio composition, lower historical loss rates, and qualitative factor adjustments. Non-performing assets totaled $1.7 million at December 31, 2017, compared to $1.1 million at December 31, 2016.

The Company’s Board of Directors voted a regular quarterly dividend of 12.00 cents ($0.12) per share on the Company’s Class A common stock, and 6.00 cents ($0.06) per share on the Company’s Class B common stock. The dividends were declared payable February 15, 2018 to stockholders of record on February 1, 2018.

The Company, through its subsidiary bank, Century Bank and Trust Company, a state chartered full service commercial bank, operating twenty-seven full-service branches in the Greater Boston area, offers a full range of Business, Personal and Institutional Services.

Century Bank and Trust Company is a member of the FDIC and is an Equal Housing Lender.

This press release contains certain “forward-looking statements” with respect to the financial condition, results of operations and business of the Company. Actual results may differ from those contemplated by these statements. The Company wishes to caution readers not to place undue reliance on any forward-looking statements. The Company disclaims any intent or obligation to update publicly any such forward-looking statements, whether in response to new information, future events or otherwise.

Century Bancorp, Inc. and Subsidiaries

Consolidated Comparative Statements of Condition (unaudited)

(in thousands)

Century Bancorp, Inc. and Subsidiaries

Consolidated Comparative Statements of Income (unaudited)

For the quarter and year ended December 31, 2017 and 2016

(in thousands)

Century Bancorp, Inc. and Subsidiaries

Consolidated Year-to-Date Average Comparative Statements of Condition (unaudited)

(in thousands)

Century Bancorp, Inc. and Subsidiaries

Consolidated Selected Key Financial Information (unaudited)

(in thousands, except share data)