The fund invests mainly in common stocks of U.S. companies of any size, with a focus on companies whose products and services we believe provide solutions that directly contribute to sustainable social, environmental and economic development (Solutions Companies). Stocks of this type of company are typically, but not always, considered to be growth stocks. Growth stocks are stocks of companies whose revenues, earnings, or cash flows are expected to grow faster than those of similar firms, and whose business growth and other characteristics may lead to an increase in stock price. The Investment Manager, as defined below, may consider, among other factors, a company’s impact on sustainable environmental, social and economic development (as described below), valuation, financial strength, growth potential, competitive position in its industry, projected future earnings, cash flows and dividends when deciding whether to buy or sell investments. The fund may also invest in non-U.S. companies.

The Investment Manager’s approach to sustainable investing incorporates fundamental research together with consideration of sustainable environmental, social and economic development impact. The Investment Manager believes that companies whose products and services produce positive environmental, social and economic development impact also often demonstrate potential for strong financial growth. Under normal circumstances, the fund invests at least 80% of the value of its net assets in securities that meet the Investment Manager’s sustainability criteria. These criteria are based on a proprietary sustainability solutions map that links to the United Nations Sustainable Development Goals (SDGs). In applying these criteria, the Investment Manager will assign each company a proprietary environmental, social and/or corporate governance (ESG) rating ranging from 1 to 4 (1 indicating the highest (best) ESG rating and 4 indicating the lowest (worst) ESG rating). In order to meet the Investment Manager’s sustainability criteria for purposes of this investment policy, a company must be rated 2 or 1 by the Investment Manager. This policy is non-fundamental and may be changed only after 60 days’ notice to shareholders. In selecting each investment, the

Investment Manager considers the extent to which a company’s products or services may provide solutions to forward-looking sustainability needs, creating positive impact in environmental, social and economic development areas. Environmental impacts may include, for example, reduction of carbon emissions and improved water quality. Social impacts may include, for example, improvements in employee well-being, supplier standards, or access to products, information, or security. Economic development impacts may include, for example, stakeholder analysis and shared value approaches to business practices, access to economic opportunity, or improvements in operational effectiveness or efficiency.

S000003881 [Member] Investment Strategy - Putnam VT Sustainable Future Fund	Dec. 31, 2025
Prospectus [Line Items]
Strategy [Heading]	Investments, risks, and performance Investments
Strategy Narrative [Text Block]	The fund invests mainly in common stocks of U.S. companies of any size, with a focus on companies whose products and services we believe provide solutions that directly contribute to sustainable social, environmental and economic development (Solutions Companies). Stocks of this type of company are typically, but not always, considered to be growth stocks. Growth stocks are stocks of companies whose revenues, earnings, or cash flows are expected to grow faster than those of similar firms, and whose business growth and other characteristics may lead to an increase in stock price. The Investment Manager, as defined below, may consider, among other factors, a company’s impact on sustainable environmental, social and economic development (as described below), valuation, financial strength, growth potential, competitive position in its industry, projected future earnings, cash flows and dividends when deciding whether to buy or sell investments. The fund may also invest in non-U.S. companies. The Investment Manager’s approach to sustainable investing incorporates fundamental research together with consideration of sustainable environmental, social and economic development impact. The Investment Manager believes that companies whose products and services produce positive environmental, social and economic development impact also often demonstrate potential for strong financial growth. Under normal circumstances, the fund invests at least 80% of the value of its net assets in securities that meet the Investment Manager’s sustainability criteria. These criteria are based on a proprietary sustainability solutions map that links to the United Nations Sustainable Development Goals (SDGs). In applying these criteria, the Investment Manager will assign each company a proprietary environmental, social and/or corporate governance (ESG) rating ranging from 1 to 4 (1 indicating the highest (best) ESG rating and 4 indicating the lowest (worst) ESG rating). In order to meet the Investment Manager’s sustainability criteria for purposes of this investment policy, a company must be rated 2 or 1 by the Investment Manager. This policy is non-fundamental and may be changed only after 60 days’ notice to shareholders. In selecting each investment, the Investment Manager considers the extent to which a company’s products or services may provide solutions to forward-looking sustainability needs, creating positive impact in environmental, social and economic development areas. Environmental impacts may include, for example, reduction of carbon emissions and improved water quality. Social impacts may include, for example, improvements in employee well-being, supplier standards, or access to products, information, or security. Economic development impacts may include, for example, stakeholder analysis and shared value approaches to business practices, access to economic opportunity, or improvements in operational effectiveness or efficiency.